Eh, I'm still more fond of just regular Halo 3, personally.
ODST isn't really worth the money and it didn't introduce anything too exciting. Don't get me wrong though, it's still a great game. The commercial was unbelievably amazing. (If you didn't see it, you should.) So for the time being, I'm content with multi-player Halo 3. By the way, I love your avatar.
[ame="http://www.youtube.com/watch?v=3ahGHjDFQm4"]YouTube - WE ARE ODST: Halo ODST Commercial[/ame]