By mastering the planes, the enviroment, learn what flying is really about, flying by VFR, or by instruments alone. Mastering helicopter flymodel or learn to fly economical with gliders. This expansion also has tons of new missions and they are great fun but it also has support for air races with other people. Flying at Reno with a 3000+ hp P51, low over the ground, trying to take the corners better than others while they are right on your tail or next to your wingtips.... priceless.
Iīm a huge fan of combat sims as well, own Lock On and itīs expansions for years now and canīt wait for Black Shark but FSX is at least equally enjoyable to me plus itīs only like $15 by now.