Just disappointing.

Big fan of silly, especially when it comes to Doctor Who, and I'll forgive any show this fun a lot of plot holes.

However, this episode has so much silly and so many plot holes that overall it's just a big disappointment. It's a shame because Tennant and Ryan have great chemistry - she'd have made a fantastic regular companion - but the storyline lacks coherency and just is not that interesting or fun.

Boring, really, and that's rarely a criticism I use of the usually fun and delightfully silly Doctor Who.