I was a single click away from getting the Rezound back in November. Thankfully though, I decided to wait a few weeks into December because of rumors of the D4 launching and I really wanted a physical keyboard.
When the D4 didn't drop and the Nexus finally released, I went and played with one in store. In my opinion it completely blows away the Rezound. I have a friend whose step-dad had the Rezound and returned it a week later because the battery life was so bad. He got the Nexus a few weeks later and absolutely loves it.
Sure the Nexus has it's flaws:
1. Battery life isn't great but it's better than the Rezound from what I've heard
2. Signal reception has been an issue for some. Only problem I have had with this was the phone dropping all signal due to what I am assuming was a hardware issue with the radio. A large part of this depends on your location.
3. Samsung's quality control is a joke.
However, I feel the positives far outweigh the negatives:
1. ICS. 'nuff said. Ok not enough, but Sense is absolute garbage. ICS is far better than Sense Gingerbread.
2. 4.65' (arguable but we're going to quote official specs here) SuperAMOLED > 4.3 LCD Yes the Rezound has higher PPI, but when the PPI are as high as they are on most devices, the difference is hardly noticeable. I believe at about 1 foot the human eye can't tell any difference beyond 300 PPI anyway.
3. Direct Google updates. Need I say more?
I know there are plenty of other factors but these are just the most important in my opinion. And that's the thing with picking a phone, or anything really. It's all up to your opinion and your needs. If you like Device A over Device B, but reviews say Device B is better because it has Feature X, but you don't care about Feature X, then you're opinion is all that matters. Example, the Nexus speaker sucks whereas the Rezound is built around Beats audio, and it comes with a pair of Beats. Sure I wanted the free Beats, but the Nexus having a crappy speaker doesn't really matter to me. I've had the phone for a month and used the speaker less than 5 times.
My advice is just play with both, get a feel for which one you like better, and go with it. Also, don't base your views on what a forum says. I did that before I bought my Nexus and was skeptical on whether to get it or not because I kept seeing all these threads about issues with it. Take everything with a grain of salt. Forums are only a sample of the population and there will always be more negative threads than good.