As far as I see it
Pros
+ Looks a nice phone, screen should be interesting.
+Android UI finally hardware accelerated
+Some cool new OS features and widgets
+Vanilla android will get quick updates
+No hardware buttons (could go either way)
+GPS that works
+Barometer (ha running out of stuff now)
Cons
-5mp camera, why not use the one from the S2, which is nearly half a year old tech.
-GPU, why hardware accelerate the UI with a last Generation chip
-No SD card, there is no excuse for this (if true)
-720p screen seems to be the default for ICS so is that a strong selling point
-CPU isnt the quickest (probably slower than the S2) but how much will that matter with Hardware acceleration?
I guess in the end it is a similar decision to all nexus phones, slightly old tech but latest software or get a normal galaxy and get the latest tech with old software.
Will be interesting to see if anything else exciting gets announced in the next few weeks