New Xbox, Recommended Games

Hey,

I bought an Xbox 360 over a month ago and I've (sadly) yet to pick up any games. Since there are so many Xbox games and series, what games should I start with! I'll warn you that I'm not particularly adept with using the 360 controller for first person shooters, but I could give it a shot. I've been looking at Assasin's Creed (I love stealth/platformer hybrids) but don't know where to begin in that series as most everyone says the first one isn't as good as its sequels.

Alright, if you've got any suggestions I'd appreciate it!

-Daniel