Yea, from what I've read Sentry has the potential to be an incredibly awesome character but, I think marvel has already screwed around with him to long. I may be wrong, the right writer could still make him work but, so far I really don't see it happening. I think he will either eventually just flop, (much like my anticipation for Star War's Darth Maul) or he will just become more of what everyone already suspects he is, another damn Superman clone.
I really think right now he could still have the potential to be completely different and so much more than Superman. Hell, I already love both the ideas of a hero being his own worse villain and being a weak scared human without his powers, whose greatest sacrifice isn't dying or losing someone close to him but, giving up his own heroism to save the world.