I'll be brief, rather than long-winded. Bioshock is by far one of the best games out for the current generation of gaming, and it will remain the best title on the 360 for about less than a month (you know, when that one tiny game called Halo 3 comes out). But for now, you can enjoy one of the best looking games with a great story, deep gameplay mechanics, and endless hours of fun. Sadly, I felt the game went on a bit too long. It's not that the game isn't fun throughout, but killing Splicers over and over just didn't stay fresh for me.
And for 360 owners, you'll have a blast playing the game twice as you obsess to to get all the achievements, 'cus you won't be getting them in one shot.