And apparently, Episode 4 is planned for release next month or so...one of the GMs posted it here.
The one thing that makes ACE different from any flight simulation game I've played is ACE is sorta kinda fast paced, but that's just me. You can change targets anytime you want and it's a chasing game. The targets will fly away from you and you gotta try to shoot at them but it's a great game if you like flight simulation. Episode 4 is supposed to add more missions and rebalance the gears.
I've never played Air Rivals since I only play North American-based games.
ACE Online is mission-based. You get experience and in-game currency from completing missions (which are fun to do). If you want even more fun, you can do PvP. But it's a pretty cool game to play when you are taking a break from RPGs.
Yea, I think they merged two servers into 1. Whenever I login, the server is probably 40% full.