I really do love my Rezound, and there aren't any issues that are make or break to me, but here are the ones I do know, coming from a year and a half from the OG Droid.
1. Battery life: If I want to go all day with lots of battery left with my phone, I simply shut off data when I'm not using my phone, and I can go 5 hours and only drop 4%. I downloaded a free 4G app that gives me a shortcut to the settings to let me switch to CDMA only, but if I do that too much, it doesn't always work well, and I temporarily lose all data, requiring a reboot. If you keep everything on, data, apps that use data, etc, using your phone not constantly sporatically, you'll need to charge by lunchtime more than likely. I have tried shutting off background data, but then my Yahoo email app gives me a stupid message asking for it turned on, and that's annoying. I haven't found a 100% foolproof way of keeping data on so I can receive emails and other data requiring things, but still keep the battery life of having it shut off with only an active phone signal. If anyone knows how to do this, I'm ALL ears! Still, using some little tips and tricks, it's easy enough to get around this, even without my extended battery which I don't often use anymore.
2. A friend tried to share her contact info from her iphone by sending it to me today through a text message ("share contact" as it was called) to test that capability out on an Android phone, and I wasn't able to save her information, or copy the number without calling it briefly, and ending the call, and adding her to "people" from the call history, seems like a pain to me.
3. If you want an extended battery, sure it really helps a lot, but putting it in along with the new back plate, and even a thin gel case over the phone will be like carrying around an old brick Nokia or Qualcomm phone from 2001.
4. ICS updates keep being delayed from "early in 2012" to "sometime this year" and that's bothersome to me, because once more phones come out with it, all others should be updated, plain and simple. The GNEX was meant to be the first, but once the next one comes, every phone at least back to the bionic (4G phones) and X2/Incredible2 (3G phones) should all receive their updates within days of each other, end of story, no excuses!
5. If you don't like social media, or don't want to use any of it on your phone, much of Sense will be wasted. I finally dumped all social media accounts (reasons unrelated to my phone), and things like "friend stream" are only used for things like Twitter and Facebook.
6. Bloatware. There are 16 things that Verizon alone put on the phone, and besides maybe one or two, they are all junk to me, and I just don't want to root and remove them, otherwise I would. I would love it if they weren't built into the ROM, but removable by users without rooting.
7. Beats is an awesome feature, and so are the earbuds, but it ONLY works on MP3's saved to your phone, not internet radio, not youtube, etc. That simply sucks. I would have bought this phone without beats, but it's sure nice to have!
So, the first is the most annoying to me, but still workable. This is the honest truth from someone who was SPOILED ROTTEN by my OG DROID and it's amazing battery life that I always babied, when I didn't need to, and now I DO need to....