Serious question. The Nexus is better in almost every regard. I would've gone with the S II, but I can see for future-proof reasons, how a WiMax device might seem unattractive - but as for the Nexus, well, it's LTE as well.
I don't see the point of this phone at it's current pricing. $99 is too high - it honestly should've been free or $20. Otherwise, the Nexus is a superior phone for the mid-range pricing.
The only downside I see to the Nexus, is the lack of an SD card slot.
I think the Galaxy Nexus is the best phone currently on the market (and as everyone here knows I'm a Blackberry fanboy, so there is no bias) but the lack of an SD card slot (which I didn't know until after I bought it) is really irritating and frankly pretty close to inexcusable...how can Samsung justify in 2012 releasing a phone SD card slot? It's ridiculous.
Android 4 ICS didn't have support for external storage at the time the samsung came up with the nexus. The android 4.1 update makes the phone become a lighting fast little beast. Is a nice option to pick when choosing a phone.