The primary way I use it is for any show on ABC, NBC or Fox that I want to watch, and there are several. It just lets me watch them whenever I want to. That plus their original stuff, but as an unlimited DVR for those networks is the main use. Well worth the $12 for me.
I've had ad-free Hulu from the day I signed up. Best $4/month I've ever spent. I don't understand the stance of refusing to get an ad-free service, while refusing to even buy a service at all that offers it because you hate ads.