I have two Gnexes since I broke one screen and had it replaced. Since I had a back up I went ahead and rooted, unlocked and installed the leaked 4.04 update. It went smooth. My speed test went from 6000 to 10000 kps and my signal strength from .96 dbm to .93 dbm at my house. I have never had the mic issues or dropping of data with either phone so I cannot comment on those issues.
Sound is much louder without having to have it maxed out and the transition from landscape to portrait is slightly faster. My everyday phone, the one with the slightly better screen, is not rooted and I will let wait for the OTA.