Both the Zoo and the Prater are fairly empty in Winter. If you want to take photos at the zoo, it was easier this time of year than I imagine it would be in the summer. Most of the rides at the Prater were not running, but a few were, which was ok, because we mostly just wanted to walk around and take pictures. The woman working the ticket desk at the zoo was confused when we presented our vouchers, but they figured it out. I highly recommend both the zoo and the Prater!