The game automatically gets a lot of points for being a trivia game that's not multiple choice. It gets some more points for the large and varied question pool.
The mechanic where you can raise the stakes if you're confident of your answer is awesome and something I'd like to see in every trivia game.
My one criticism would be that I wasn't a fan of the subset of questions where you needed to guess how people answered a survey ("what percentage of men buy bottled water every day" or whatever). This isn't really stuff that anyone could actually know and that's fine. However my ability to guess accurately is going to depend on external factors like the country or region where the survey was performed, the sample size, and the age of the study. As it is now, I just feel annoyed when I get one of these wrong and lucky when I get one right.