Ever since I picked up my Epic at launch I've missed Cyanogen from my G1. While it isn't perfect in its current state I can't imagine using anything else. It's responsive, it's lean, and it extended my battery life by about four hours when I installed it. There's a list that doesn't work at the moment (911 emergency calls, 4G, several video codecs including Youtube HQ, video recording) but the things that work are fantastic.
I was about to jump to Verizon for a different device, but with the breath that Cyanogen gave my Epic I'm going to ride it out.