Stuart and Karolina's place was really great. That was our first trip to NYC - we were very positively surprised how close Williamsburg is to all the Manhattan's attractions. Staying there will save you a lot of time and thinking on your commutes.
The flat itself is plain great, just see the photos. It's a shame the weather didn't really permit us to use a terrace - make sure you do if you can!
We enjoyed a lot what seems like a small detail - availability of a recent Lonely Planet guide for NYC. It helped us much more than I initially expected!