Arkham Asylum is definitely better than City in my opinion.
Hell yeah. It was actually in the same league as the contemporary Uncharted game. One of my favorite single player experiences ever. Arkham City was... Overall meager at best.
I guess ACR... when i 1st played i thought it was awesome...
But then i realised i had to delete the patch to get the Sage trophy so i did the entire story a 2nd time and as Kaswa101 said, some parts felt useless.
Worst game of 2011 that was supposed to be awesome has to be Need For Speed: The Run
it had everything.. Beautiful environmnets, awesome graphics, decent attempt at a story mode.
All crushed by terrible broken gameplay
Flip the coin however, Portal 2 was easily the best game of 2011, understood it's not for everyone, I mightily enjoyed the hell out of it though.