My gosh, you got ripped off. I got it on PS3 launch day. Premium + Gears of War + Ghost Recon Advanced Warfighter + Ridge Racer 6 + Xbox Live Arcade Unplugged for 450CDN.
The only games I'm really playing are Gears of War, Rainbow 6: Vegas and NHL 2007.
NHL 2007 on the 360 is pretty cool. Apparently, it's a little lacking content-wise in terms of sheer options, but the new stick controls using the second analog stick is pretty cool. Makes it quite a different experience than the other versions.
Gears + Vegas are shooters, but coop makes them awesome.
As long as devs keep churning out solid coop titles, the 360 justifies itself easily for me. It already has.
Not really planning to pick up Mass Effect until it hits the bargain bin, but my brother is looking forward to it, so maybe we'll play it before then.