1. It has the super creepy factor.
2. Great companions! Madame Vastra, Jenny and Strax!!! Oh Strax! I love thee!
3. Nods to Tegan...I love how 11 has been mentioning things from his past this season, it is something I wish he'd do regardless of it being the 50th anniversary of the show. He has a past and he should share parts of it with his friends.
4. Tom Tom..the little boy GPS!
This episode also makes you wonder if the BBC has bought stock in red cosmetic paint.
For a season that has been primarily hit and miss episodes with a companion that you aren't sure whether you are supposed like or feel anything for her or not, this was an episode you really liked.
Oh and props for craziness
This was by far one of the best episodes in this half a series.
Also, wouldn't is be kewl, if Madame Vastra, Jenny and Strax would actually be REAL companions to the Doctor..and different.