I have refunded several games (I have over 300 games in my library).
I will watch reviews, watch people play it, but those are not the best ways to tell if I will like a game. I've watched tons of people play games that seem like fun only to buy them and absolutely hate them.
If there's no demo (no one makes demos any more), the only option is to buy it, play a little and see if I like it. If it sucks, then it gets refunded.
I think 2 hours is too short of a time for a refund though, especially when steam starts the timer as soon as you launch the game. You might spend 2 hours trying to get a game to work and never actually play it, or just sit at the main menu for 2 hours, or some games takes longer than 2 hours to get to the meat of the game, and you're out of luck at that point.
I guess it's better than nothing though.