Sentry's powers are definitely the same as Superman, but that in itself makes him a bit relatable. Superman's an icon. Everyone knows of his powers to some extent, and so his powerset's a good place to start for characters who are almost "Superman gone wrong". Just that one seemingly small difference between the two is a VERY clear division that makes Sentry unique.
I think Sentry's powers are actually Bob Reynold's idea of what a Superhero should be. His potential is well above even his fictional Sentry, and the equally fictional Void. I doubt he'll really turn into a long time character, because once his problems come to a head, he will either A: Deal with them and become Superman. (lame) B: Die. C: Unlock his full potential, ascend to godhood. I think starting as an obvious Superman knockoff and branching out can still breed a good story, just for the millions of different ways that one can take with it.
I think the realization of his true power while dealing with his psychological dilemma could be cool. I dunno. It could end up terrible, but I think Sentry has potential. We haven't seen enough.