I've found most of Gatiss' episodes fun and enjoyable. Then again, I'm not exactly super-picky over Doctor Who in general. Favorites from his list would be The Unquiet Dead, The Crimson Horror, and The Empress of Mars. The only one I've really felt "meh" about was Sleep No More. The story idea was interesting, but it lost something in the execution. The lack of resolution was especially disturbing - the Doctor and Clara just escape in the TARDIS, no stopping the monsters, no mention of what might happen to the populations the station serves, etc.