This has been mentioned elsewhere, but it took some digging to find mention of it so I figured I'd bring it up for those who haven't come across it yet.
A major disappointment in the RAZR (from Bionic) for me was the sound quality coming from the headphone jack. I stream Pandora with my smartphone(s) in my car (and headphones), which has a fairly impressive sound system that reveals lower quality tracks for what they are. My Bionic sounded fantastic with this setup while streaming Pandora with the high quality setting enabled. The RAZR however, sounded like my ipod nano, which made my music sound extremely compressed; flat, uneven sound levels, and an overall tinny sound. Once I heard the fantastic sound coming from the Bionic, I was desperate for a solution to the RAZR.
The Solution: Disable (or adjust, if you prefer) the built in audio effects software. It is very easy to do, simply go into Settings > Sound > Media Audio Effects > Wired stereo devices. Uncheck "Enable audio effects" to disable them.
Some have suggested this software equalizer stacks with other equalizers in music players or stereo equipment and the combined effect degrades the experience. Even if you have no complaints about the quality of sound coming from the headphone jack, you still might want to try this. There is the option to disable the same effects for the speaker on the phone, but I don't use it so I can't comment on the experience after disabling its audio effects.
Once again, after disabling this feature, the RAZR has made me extremely happy!