Well from what i've heard about the music from an extremely reliable source, it SHOULD be pretty epic. BUT, as we've heard from recent soundtracks such as SAW... it could be a **** hits fan track.
Maybe SAW's wasn't very good because they were restricted to making something new for SAW [which already has an epic soundtrack] that was original, yet just incase the sponsorship got pulled, they could keep the soundtrack for a while [It doesn't really relate to SAW without the voiceovers, lets be fair]
Which is why i'm hoping the soundtrack for Thirteen shold be half decent, because they are their own predecessors. They know what they need and want for their own ride, and have pulled amazing music out of the bag for rides that follow similar stories at Alton.