As for the pros and cons of the S3 versus the Rezound, having owned the Rezound, this is how I see them breaking down:
- A faster, more efficient processor
- 2GB of RAM (not only is the extra memory noticeable in everyday use, but it also makes the device more future-proof)
- Better battery life
- Larger screen (half an inch)
- Thinner and lighter
- Touch Whiz has some great built-in features
- Reception isn't quite as good, although it's much better than any other Samsung Android device that's been on Verizon, and it drops signal less than the Rezound.
- Touch Whiz - it's a little cartoonish for my taste (but then again, so is Sense), but that can easily be taken care of with a custom launcher.
Both have great cameras (I'd give a slight edge to the camera on the S3, but it's extremely slight), 720p displays (between the two, I tend to prefer the Super AMOLED of the S3 myself, but that's personal preference), and both support SVDO (simultaneous voice and data over 3G). The S3 bests the Rezound in pretty much everything, but I'd say it's not a huge step up. Unless you've damaged your Rezound and have to get a new phone, or unless you're like me and constantly change devices every couple of months, you're probably not going to see a massive difference in switching from the Rezound to the S3. At this point, unless your Rezound has bitten the dust or is full of problems, I'd wait and see what's coming around the corner with the rumored 1080p HTC, the possibility of the Galaxy Note 2, and information on the next Nexus (or the multiple Nexus devices).