I watched up until Company Man, maybe an episode or so after it. Even Christopher Eccleston couldn't save it.
For the record, Ruzbeh, I thought the show started out well enough (I found the pilot kind of boring, but it was clear it was setting things up, and for doing that it was acceptable), but it lost serious steam right when it should have starte really cookin'--when introductions were over. After the first 4 to 6 episodes, it was just kind of meh for me. . .until mid-season, when it seemed like with full knowledge of the show being a hit, they turned shit up. The mid-season was pretty great, and I figured that this was a case of deserved hype. But the same thing happened again. And yes, I did like Eccleston's character, but honestly, I won't watch something just because Doctor Who was doing a guest spot.
In short, I think the most problematic part of the show is that it's overburdened with bad characters. I hated Hiro at first because he was clearly a bundle of idiosyncracies and Japanese stereotypes rolled up into a racist popcorn ball, complete with shit getting stuck in your teeth. Puzzle me bewildered when a few episodes later, I find him to be one of the more interesting characters. When a complete stereotype, bordering on racist, is your shows most interesting character, you've got problems.
Claire isn't really that bad, but I hate the tendency of TV shows not to characterize female characters well. Claire's main character trait is that she dresses like a cheerleader and is hot. The Petrelli's, obstensibly sort of the main characters, are both boring, and the worse of the two seems to be bordering on Spider-Man levels of emo sometimes. Niki and everything, everyone associated with her is embarassing. When she, or one of her associates would appear onscreen towards the end of an episode, you could rest easy with the knowledge that turning off the show, smoking pure heroin, and coming up with your own ending would probably be less distinguished mentally-challenged. And feature better acting.
And there's also the show's tendency to not show action onscreen, despite being a show about heroes. I hear this gets more annoying just past where I quit, but it was still rather noticeable from where I was watching.
But I put 15+ episodes into the thing. That's more of a fair shake, that's like 15 opportunities for it to get its act together and live up to the tantalizing promise that would frequently peer through the edges.