I heard reports of the music skipping if it was playing in the background while using another app. If it's happening while in the foreground, try quitting background apps.
I heard a difference with the DTS versions but it wasn't as dramatic as the demo with zimmers' voice coming from the different "speakers." The DTS version had fuller bass, and I heard a few cool directional effects, but that's about it.
Also, I'm a broken record on this (see my thread below), but be sure that you don't delete the app on your phone if you downloaded the full album using the redemption code - if you delete the app, the DTS tracks are gone forever, and you can't redownload.