In my opinion, one of the worst sites, software wise, is
Pacific Poker. I played there because they gave me a $10 no deposit bonus. There were times when i couldn't see my cards. There were also times where I could see my cards, but couldn't see the buttons to choose what to do. So i timed out, and had to fold. Also, it seemed like there were a lot of bad beats there. It did have some decent freerolls though.
I like
absolute poker, but the value for their freerolls is just brutal. I once played one of them because i was bored. There were 2000 people, and I finished 8th. I received absolutely nothing. Only the top 5 in the tourney received anything. Waste of 5 hours.
I also don't like
Party Poker, or any of its affiliates, simply due to their lack of freerolls.
Party Poker is supposedly the most successful online poker site, yet they can't afford to even have something like a $100 freeroll? That really bothers me