As I am in the US I popped into a Best Buys and tried out the Nexus S. It has a gorgeous screen, good cameras and nice touch to it. I only looked at it for about 15 minutes (the store was crazy) but liked it enough to buy one to possibly replace my Nexus 1. Gingerbread seems like it has a new nice features and the lack of a trackball didn't seem to be a hindrance since the editing functionality in Gingerbread is more like what you get with IOS4.
The lack of a memory card option isn't a major for me since 16G should be enough since I have lived within 8G okay with the N1.
I also like the size since I tried a number of HTC and Samsung phones while in BB and I find the larger screens just a bit too bulky for me.
You can read full reviews on other sights but so far it seems like a nice upgrade from the N1.
I have had problems with my N1 but am I am waiting for a replacement from HTC. If the replacement works fine and I know Gingerbread is coming to it, I might just sell the Nexus S when I get home. It's still in the case unopened and I don't expect to open it until I get home and I might not even do that if the replacement N1 works fine. (My N1 has had a problem with the camera imparting a pink tinge to all pictures and erratic touch).