The evil guy/monsters were terrible; felt like there was nothing actually threatening the Doctor.
Also, this episode just seemed like a bombardment of information. They could've subtly fit the information in this episode into previous episodes, but for some reason they left everything until the last minute to reveal. As a consequence, Clara's whole storyline was completely overshadowed by the John Hurt thing, which is a shame caused by bad writing.
Honestly, I still feel like I don't know who Clara is. I mean I know why she was 'the impossible girl' but who she is/her character wasn't very well written. Just have to say, I've really started to dislike Strax - his novelty has completely worn off.
In its own right the episode wasn't that good imo, but I guess if you look at Doctor Who as a whole it was really good.