I was into flight sims from around the age of 4 too.

A lot of flight sims require hours, or even months, of practice, especially if you want to fly according to the rules / how real pilots fly. Back in June I finally picked up Falcon 4.0 Allied Force, and I have yet to really knuckle down and learn what all the switches do. For me it's a big step up from Lock-On Modern Air Combat (mainly because I played a couple of the older Flanker sims that Eagle Dynamics also developed, which have similar controls to Lock-On). Printing out the huge manual you get on the CD seems like a chore in itself, not to mention a bit, well, environmentally wrong (who's gonna save the trees, man??

). Once I get up to speed on it and figure out how multiplayer is meant to be set up I might ask Mika for a coop dogfight or something.
Part of the enjoyment that I get from flight sims is the satisfaction of having flown according to the flight plan and landed safely, which is even greater if the aircraft has damage and stuff like that. But sometimes just doing aerobatics and screwing around is fun too, like in the first Flight Unlimited sim, which had an emphasis on performing aerobatic manoeuvers. Stressing out the the Sukhoi Su-31 until it disintegrated gave me many moments of fun.