This was another of the top stories of the series. Great performances from Matt Smith, Karen Gillan and Arthur Darvill as well as all of the supporting cast especially David Walliams as the Gibbis.
A simple enough story with the TARDIS crew trapped with four other characters in a hotel that is not really a hotel. Each character has their own room wherein their greatest fear lies. When they see that fear, they fall back on their faith to support them, which is their inevitable undoing as that faith is what the creature in the hotel feeds upon.
A simple concept but what makes it great is how Toby Whithouse explores those fears which allows for great character development. We learn that Rory has no faith and as such is the only character the creature is not interested in. We learn that Amy's greatest fear is abandonment which makes total sense given her character background. And her faith is in the Doctor of course although to save her, he must break that faith.
The other characters in the episode are also explored quite well given the 45 minute running time. In just a few brief scenes, we get to know the psyche of the Gibbis, Rita, Howie and Joe surprisingly well. Part of this is due to Whithouse's script, part is the fine performances and part is the fantastic direction from Nick Hurran. Hurran utilizes the current choppy editing technique of Michael Bay and his ilk to great effect to show us the gamut of emotions the characters experience upon seeing their greatest fear from terror to giddiness as their faith overwhelms them.
Matt Smith gives a great performance as we truly see the frustration and agony he feels as he's utterly helpless to prevent the deaths of his new found friends. One of his best as the Doctor so far.
We do not get to see the Doctor's greatest fear which may be for the best as fans would probably argue about it relentlessly but it involves the cloister bell. (My guess would be him succumbing to his darker side ala the Dream Lord/Valeyard).
The Gibbis is a fascinating idea for a species that at first glance seems to be typical cowardice and willingness to be subjugated which leads to some great comedy but as the Doctor later points out, his species' cowardice hides a far more aggressive characteristic than is expected as they are willing to sacrifice any one and any thing to survive making them one of the most ruthless species out there. David Walliams is perfect as the Gibbis combining comedy, a sinister undertone and a hidden smugness as well.
Amara Karan is great as Rita portraying a legitimate potential companion which makes her ultimate fate even more tragic.
There's a great classic series nod of linking the creature to the Nimons which of course makes my inner geek smile.
The seeming departure of Amy and Rory and the reasons behind it make total sense. It was a great moment both story-wise and emotionally. At this juncture I would say its best to leave them there at this point, but as we now know, they are rejoining the Doctor for part of next series again. This departure was merely a story reason to get them off the TARDIS so that the Doctor can confront his fate at Lake Silencio. I really have to wonder if their real departure will be as satisfying and appropriate as this false one was. I hope so. And I hope it doesn't end with their death(s).
Here is my list comparing the twentieth stories for each Doctor from most to least favorite:
1) Blink by Steven Moffat
2) The Time Warrior by Robert Holmes
3) The Caves of Androzani by Robert Holmes
4) The God Complex by Toby Whithouse
5) The Myth Makers by Donald Cotton
6) Image of the Fendahl by Chris Boucher
7) The Space Pirates by Robert Holmes