Yeah, it sort of always seemed like that though. Season one was just so awesome it always felt like the next would be like it, but it never was :: It did seem promising, looked like they were going in the same direction as the X-Men comics, with the "mutants" coming out. And X-men is always good.
What kept me watching after season 2 was the promise of some kind of epic conclusion at one point. Namely, the face-off between Sylar and Peter (which was actually foreshadowed in on of the episodes). All the way to the point where it just kept dragging on and on, and then they even neutered Peter's ability. Disappointing stuff.
But this time it really looked like they were turning the show around.