Visually, IL-2 is a beast. I'll stop short at labeling it as one of the year's best looking games, but it puts up enough of a show that it at least makes the runner-up list. Planes are replicated to authenticity - right down to enemy pilots in cockpits. During play, you can actually zoom in on pilots and watch their reaction once they realize they are in your sights. Once you've got a target dead to rights, you can enjoy all sorts of beefy explosions, including wings shearing off planes and large gouts of flame and smoke. There's even a nice little bit of oil splatter when you get too close to a soon-to-be-down enemy.
Levels are just as impressive, though you probably won't appreciate it until you get into denser cities like Stalingrad. A lot of work went into making sure everything was fully realized, right down to the smallest of farmhouses. I've never been to Europe, so I can't vouch for authenticity, but cities look like reasonable facsimiles. Buildings are laid out in a logical fashion, so it isn't too hard to see them as a functioning city and not just a bunch of building models tossed out in a random formation.
Just as much attention has been paid to audio. Planes roar, sputter and choke depending on altitude and condition. All of the explosions and other effects are accompanied by satisfying sounds, particularly falling bombs and their explosive wakes. There's no better feeling than to watch a giant battleship ignite into a symphony of flame, smoke and noise. The sounds of battle are accompanied by a masterful score.