Totally agree, got mine last week, and the s4 is leaps and bounds ahead, personally i cant tell much difference between the 2 on music playback, but im also not an audiophile so for me i just want some background noise while i am driving or working. I have never looked for more then that so my needs are met 100% with it. Although i do like the advance to next track and pause/play the rezounds headphones did better then the volume control and pause that the s4 does.
one area i give a very small advantage to the rezound on is, phone single strength, until you read the manual and realize that you have to hold the s4 a special way, the rezound beats it hands down, after the change in grip, they are about even. Apparently you cant just hold it in your hand with your palm against the lower back of the phone. In the manual it points out that is the location of the antenna, and if you are going to hold the phone then hold it with your fingers and keep distance between the bottom area and your palm, or to hold it near the top....
The battery however, that is no contest, you couldn't even get half the time out of the rezound with 2 batteries., add to it the bigger screen, better speed and the like, s4 = much better phone.