Il-2 Type 3
The Il-2 was for the longest time a very uncommon aircraft, downright rare to be honest, but seems to be making a bit of a comeback. Often though you will see them be spawned pointlessly on a runway when all the fighter hangers are down (bomber hangers spawn Il-2s). Irregardless, the main historical strengths of the Il-2, armour and firepower, are fairly well modelled when dealing with tanks and other vehicles though the Il-2 also shows the historical vulnerability to true fighter aircraft. Used as a local defense aircraft though the Il-2 can be quite effective though using it offensively tends to be almost suicidal and many aircraft make better attackers.
Il-2 Type 3
The Il-2 isn't going to impress you with speed, it is truely slow at only 245mph at sea-level (no WEP option). Increases in altitude come slowly and offer little improved performance. The best you can achieve is about 260mph at 8K and performance drops off rapidly above that altitude. Climb rates are punishingly slow at only 1,400ft/min so don't plan any time climbing except what you may need in order to make a good bombing run from decent altitude. A serious problem for the Il-2 can actually be that some higher altitude fields in AH already place the Il-2 outside of the low altitude performance envelope it requires. Fuel duration is also a problem, only 32 minutes and considering the low criuse speeds involved that doesn't get you very far. Best to keep your fights close to your own field.
Standard are two 7.6mm guns (750rounds/gun)and a pair of massive 23mm VYa cannons with 150 rounds/gun. To the rear is a single mounted 12.7mm machine gun with 200 rounds, which could cause attackers some concern but being only a single mount doesn't tend to add much to your rear defense. The 23mm cannons can be very destructive against vehicles, or structures, but it seems that you need to get fairly close in order to punch through a heavily armoured target. Being wing mounted, convergence can be a problem and it seems people set the convergence out to the maximum of D650 to get some longer range shooting potential. That results in the best range for the cannons being a little further out than would be typical in most fighters. The 7.6mm guns are essentially useless except as a last ditch weapon. Complementing the guns are options for both rockets and bombs, with the bombs being in wing-pod mounted internal bays. This is an unusual layout and requires you to remember to open the bays before using the bombs, but imparts an advantage in less drag when the bays are closed. The rockets are quite effective against armour, and the 250kg bombs are a good size, making for a decent loadout.
13, 580lbs, 47' 11" wingspan, 38' 2" long.... doesn't sound like something that should be very maneuverable but actually the Il-2 isn't all that bad. You won't beat a turn-fighter but you may be able to avoid a little bit of trouble if it comes your way. I've found the maneuverability of the Il-2 feels sloppy though, it seems to be pretty unstable and heavy on the controls. This is probably because it is usually quite heavily laden with weapons and it simply fly so slowly that just generating lift is an issue, let alone turning. Stalling the Il-2 is not all that fun, it flops around like a bit of beached whale but tends to get pointed nose down and accelerate back into control which is fine as long as you have a bit of altitude to work with. At low speeds you may find very little aileron response though making reversals at the top of zoom climbs a bit of a problem.
Flying the Il-2
The real shame is that the Il-2 isn't more useful and popular but a couple of factors conspire to keep it relegated to something that only shows up from time to time when a base is under attack by GV's. The key knocks against it are a lack of speed, only a moderate weapons load, and a lack of survivability against large caliber hits (which are very common). Now, nothing in the game can really survive large caliber hits nearly as well as the Il-2 except a much larger bomber, but with it's slow speed, it tends to be an easier target and gets hit more often than a faster fighter. The Il-2 is one of a few planes that can actually survive an Ostwind hit, sometimes two, but it simply presents too slow a target to avoid getting nailed most of the time.
Typically, the Il-2 is used in the anti-GV role and can be quite successful as it can absorb some hits from defending vehicles and continue to operate. You don't want to take lots of hits, or large calibre hits, but you aren't nearly as likely to lose something important to a couple of pings of .50cal or less. I tend to climb and use the bombs first, then rockets, then guns as the bombs will require the most altitude to use and I don't want to have to worry about climbing later in the fight to get sufficient altitude for the bombs to arm. I will also get rid of the most dangerous units with bombs in that fashion, typically any air-defense vehicles (Ostwind especially). Rockets are very good against Panzers once you learn how to aim and you can launch them point blank without concern of the pintle gun knocking you out. Panzers also offer more slowly moving targets. The cannons I save for the end, use them against M16's, M8's, LVT's, or PT's and then hit Panzers from the rear while flying only a couple of feet off the ground. High angle attacks are best of course but typically by this point I'm running in the weeds and don't want to climb.
You won't want to get caught in large calibre fire though, try and avoid anything that can hit you with more than a 13mm/.50cal round. You may survive two or three times the amount that would normally take down a fighter but chances are if he has you in his sites you are slow enough that he'll land a lot of hits in a short time. If you stand infront of 20mm or greater you are still going to get hurt pretty quickly.
To beat it
One would think the Il-2 should be easy prey, but that's usually not the case unless you catch one just taking off on the runway. Often they act like bait to attract suckers who will dive in and expose themselves to other friendly fighters in the process. The Il-2 is something like a Val or SBD, it is surprisingly nimble, flies so slowly, and makes such a small turning radius, that it can be very difficult to judge each attack pass on one. The Il-2 also has something those other two planes don't, a fearsome punch if you find yourself nose to nose with one. Always remember, that most fighters are going to have at least 100mph of advantage, if not closer to 200mph, on the Il-2, so closure can occur very quickly without much time to adjust.
If you find yourself with an Il-2 on your tail, try and extend if you think you can get out of the D600 or so range of the cannons. The Il-2 is likely to be greedy and fire until you are clearly out of range or he runs out of ammunition, so remember that. Il-2 pilots tend to find few honest opportunities for fighter kills so will push the point aggressively. Make most maneuvers up into the vertical and use your climb and acceleration performance advantage to the maximum. You should have clear advantages in both of these areas regardless of the fighter you fly and can exploit the Il-2s weakness. Keep your speed up, honestly an Il-2 should never have any sort of speed advantage at merge unless you've allowed yourself to get dreadfully slow. Even if you find yourself very slow you should be able to spiral climb and quickly sap all the energy out of the Il-2. If an Il-2 has a snapshot, avoid aggressively, you cannot afford to accept even a single 23mm hit as it could end the fight quickly.
Attacking an Il-2 shouldn't be a problem where you find yourself losing advantage, but it might be a problem in getting a kill. Snapshots seem to have pretty minimal effect unless you can land a large number of solid hits with large caliber guns. Try and energy fight as much as possible because the Il-2 is completely un-suited to this style of fighting. Never accept Head-Ons, you simply cannot compete in terms of firepower or survivability and you're much better to break off the attack and come back for another pass later. Be very careful with the quick turn-rate and small turn-radius of the Il-2, it can surprise you like a Zero and you can find yourself facing an unwanted Head-On. If you do manage to saddle up on an Il-2, don't be too worried about the single 12.7mm rear gun, but also don't plan on exposing yourself to it for long. It's not the type of weapon that will knock off a wing, but it will damage your plane and force you to rtb. Often a quick burst to the tail will knock it off, or kill the tail gunner anyway. Look for the Il-2 pilot who decides to rely on armour and the rear-gun for defense, they are easy to kill with almost no risk and a lot of people fly the Il-2 like this.
Some additional points, slowing down to fight an Il-2 often leaves you very vulnerable to almost any other enemy in the area, so is not advisable. If you get that slow and low you are just as likely to find yourself in trouble before you even really get a good shot in on the Il-2. Il-2s are actually used like bait sometimes. Also, watch for the overshoot and try to escape upwards if you see one coming. When fighting something so slow it is easy to misjudge and overshoot so quickly that you find yourself out in front before you react. The Il-2 can make you pay dearly for this mistake so you need to ensure it doesn't happen, and if it is unavoidable that you take quick defensive actions.