I knew I was going to love Pacific Rim (giant robots and monsters? Sign me up) but I didnt expect the horror element of it and exactly how menacing each kaiju would be. I can easily rewatch it many times.

To the original question, from recent memory a film that surprised me was Dungeons and Dragons Honor among Thieves. The IP didnt have a great track record in film, but this one was entertaining, funny, heartwarming, and highly recommended.