I think it's just that "Heroes" is totally about the story, and the characters are secondary to that - and ... even though I like almost all of the characters, there's no-one I just LOVE and feel compelled by.

Wow. That's exactly it. I've been struggling to put into words my issues with "Heroes," because I want to love it, and I haven't been able to figure out what it is that keeps making me watch it and yet not want to think about any of the characters at all the moment they are off the screen. I have kept thinking - interesting stories, and I want to know what happens next, and Hiro's awesome, but...why is it not eating my brain like say BSG???

Thanks for figuring it out for me :)