Here is what I like Nexus S
1. This will be always the first phone to receive an update from google because it is google's flag ship phone. They will always push out updates on this phone first.
Here are things that I hate about Nexus S
1. No SD card slot with no option for 32GB.
2. No HSPA+ support for T-mobile.
3. It's unlocked, but BS and useless anyway because it only works with T-mobile 3G not AT&T's 3G.
4. It's almost 2011, the specs are so 2010. Wait for 2-3 months and you will start to see dual-core phones with much better camera
5. No HD recording from the start. WTF? It doesn't shoot 720P Video
If you have T-mobile, then this is the best Android phone yet, but it won't be for long. I will give it about 3-4 months before Motorola, HTC, Samsung and LG will bring out dual core phones with better specs.