Short first impression: it's good!
And online players are tough beasties. I got one win, only when I played in Dutch, and even then I only won one out of three I think.
Custom question sets and playlists work, but it's a shame a little bit that you always get all questions that you put into your set. So that takes the randomness out of it a little, and makes them not that useful for repeating, unless they are educational (which is what I'm thinking about making use of, like creating pop-quizzes to train certain kind of knowledge)
The second online round isn't broken - you can select and deselect right till the last second, which means you can delay your choice and fool others by first selecting the wrong choices. It's also darn hard, hardest round, with multiple selections being valid.
There is definitely room for growth (from what I've seen I think more online modes, custom mode sets online, random question selection from user created questions, more interactivity), and I haven't checked out the offline part of it all that much yet, but it's all very good, smooth and easy, and so far, I'm very pleased.
I'm also impressed at how much Dutch content has been created already and there are plenty of players even in Dutch only online games. This excellent language support means I can definitely recommend it to my colleagues including those with kids.
From the looks of things they made everything very suitable to expansions, so I think this game will have a long future!