This show started with an incredible premise. Everyday people starts to have superpowers. Each one discover their power and try to deal with it. There is also serial killer Sylar who discovers a way to kill these special people and take their powers.
Like the brightest of stars, they burn hottest but don't last. This show fizzled as the story got more and more complicated. The vast number of characters with unique superpowers gets out of hand. There are too many to maintain. Like a truck overloaded, it just couldn't continue and rolled over. By the 2nd or 3rd season, this show gets increasingly convoluted and becoming almost unwatchable. They try to reboot the 4th season by adding a whole new set of people and a circus. Of course, it didn't work and the show was canceled. The first season is a 9 or even 10 but it's a long slide into 4 territory at the end.