I am currently building a new rig for my friend. He is getting a 2GB GTX 660. It helps that his favorite game is Assassins Creed and they are bundling it free at the minute from selected retailers.
Head on over to my post to see his specs if you like. http://www.overclock.net/t/1329829/intel-budget-system
Tom's Hardware is the most recognized reviewer within the community and they rave about the GTX 660. Here is the link to the review http://www.tomshardware.com/reviews/geforce-gtx-660-geforce-gtx-650-benchmark,3297-24.html
I have researched this card over the last few days and the findings at Tom's are pretty much on par with all the other review sites. As most games nowadays are becoming Intel/nVidia optimized I would lean towards the side of compatibility as opposed to awesome frame rates. Fixes for games sooner and less glitches, due to nVidia test beds.
As always AMD has a viable option and shouldn't be discounted. Go with what you want and be happy with it. I am, you only have to read my post and see me stand up to the AMD boys. Its your PC mate.