Just upgraded from a droid 4, loved that phone but the battery was getting worse everyday. There were also small things that drove me nuts, sometimes the gps would lose signal for no reason or it would put me like a mile off track. And also, i used it for music via bluetooth in my car and i thought it was my car stereo going bad but music just started sounding terrible. So, on a whim i went out and got the new phone and everything that was OK about the droid 4 is AWESOME about the Razr HD. The sound quality through bluetooth is 10 times better, music sounds the way it's supposed to now(is there better audio hardware in the HD or is it a software fix?) and the GPS works great, i've been using it around D.C. all day and it never loses track of where i am. Also, the screen is absolutely beautiful. I had no complaints about the droid 4 screen but this one manages to blow it away. And of course, the battery. Two days ago i started using my D4 at about 6:30 in the morning(moderate use, some light browsing and wordhero for 30 minutes or so, few short phone calls) and by 3:00 pm i was at 15% battery. Today i had the same schedule, started with a full charge on the HD and i used the hell out of it all day, it was hardly ever in my pocket. At 3pm, i had 65% battery life. I was debating getting the Maxx but it looks like i wouldn't need it anyway. I can't wait for official JB update.
If anyone is on the fence about upgrading, the HD is a huge improvement over last generation droids. If you're eligible for an upgrade you should totally go for it.