I'm new to anime, and am currently under the tutelage of Ryoji-sensei. Every show he suggests is completely amazing, and so I've come to expect greatness from his suggestions. Here are two surprises which came from outside his suggestions:
Good Surprise - Aku no Hana (Flowers of Evil). Yes, that rotoscoped one currently airing. It's largely dropped its early efforts to give off a horror vibe, and instead has turned into an interesting exploration of characters. The show is very polarizing, yes, but that probably means it's trying new things and pushing some boundaries. In an industry as long-lived as anime, I'd imagine that's a good thing to do, from time to time.
Bad Surprise - OreShura. Man... That show had so much going for it: engaging characters, a great first 2/3rds of a season... and then it seemed the writers could never decide what to do with the narrative. The ending felt dishonest and out of place, and left so much promise hanging. (The surprise was -- for the first time in my experience -- a show with a mostly-great season and great characters tripped at the finish line)
EDIT: It's okay, Kotomi. We can still be friends : ).