I played Crimson Skies a LONG time ago when it first came out for PC. It was fun as hell with the multiplayer (hell, and single player). The engine was very solid, that lead to a great ability to have awesome dog fights. The "capture the flag" mode was awesome too, you have to fly through airplane hangers to get the flag
I wouldn't compare it to Halo, they are two completely different games. I personally have always had more fun playing CTF Halo. I'm not a big fan of the deathmatch though.