One thing that I will note is, for a very early alpha, so early its called technical alpha, the servers and features that are in have been rock solid. Kinda expect that from a Blizzard game, but just pointing out that the back end seems really good. I can't put a finger on why, but the game is definitely growing on me. I haven't had the urge to log into LoL the last couple days. Been playing 5-6 matches a night of this.
I think the champs and talents are really well done and interesting. I've been playing Abathor, Nova and Diablo and each has several interesting things about them. Even the supports are really fun.