Visited Wonderla with my husband and some friends. We had a lot of fun. We were there on a Saturday and it was perfectly fine, some crowd obviously, but not like jam-packed. Rides for all tastes.
Just watch out for the wandering hands in the Waves swimming pool. There is a separate area for ladies anyway and sadly I would advice all girls to use it. Even if they are there with their partners. The drinks and snacks are sold at reasonable prices. The washrooms and changing rooms are very good, organized, with lockers and hot shower. Have fun!