The Eleventh Hour is a Steven Moffat script. The Doctor is introduced to two new characters - himself, and Amy Pond. He initially meets Amy as a 7-year old, then returns just as her adult self has begun to doubt he was real. It's reminiscent of Moffat's previous script for The Girl In The Fireplace, perhaps my all time favourite episode, and also Audrey Niffenegger's The Time Traveller's Wife where the timelines are a little more entangled.
The Doctor is also getting a feel for his new persona, trying out different words, phrases or looks. He's a little disturbed but it's never quite as dark as those first few manic depressive Colin Baker episodes. There's some bits about an alien prisoner on the loose but do we really care about all that sci-fi stuff? Well, maybe. This is a strong, witty episode, a good start to the series, and Matt Smith and Karen Gillan already appear confident in their roles.