Good surprises... I have a lot of stuff I thought were 'good surprises' but usually I pick up anime based on recommendations, so those are small surprises.
Kino no Tabi was really more awesome then I thought it would be. Chihayafuru ended up being my favorite competition anime ever. Recently I discovered the joy of mahou shoujos, and guess what? Heartcatch Precure is an amazing series.
Oh, and first time I tried it, I didn't like Mawaru Penguindrum much. Then I picked it up again and watched it through, and it was freaking great. One of my favorites.
Bad surprises, not that much either. Well, this season I had some bad surprises, with the two shows I hyped (Suisei and SnK) ending up being a tad disappointing.
Yeah, well, actually there's one. Now I'm going to get beaten to death and Ryoji's going to take out his guns, but I'm watching K-On and I don't like it. I find it funny a third of the time at best, I can't seem to get myself to like characters like Yui or Ritsu: it didn't hook me. The concept of making a music band and ending up doing nothing instead kinda irritates me. I can totally like anime where pretty much nothing happens but girls fooling around (I love Lucky Star). But, K-On? I can't.