Prepare for some spoilers. Don't say I didn't warn you. By the way, Matt Smith is the 11th Doctor (or the 12th, depending on how they spin David Tennant's extraneous regeneration) in case you didn't know.

Actually, it's not that bad. From an article posted on The Doctor Who News Page, it is learned that his new companion, Amy, is a police officer. In a few photos, he also seems to be wearing the remnants of Tennant's outfit. From the description, the Doctor is probably going through some post-regenerative trauma. When has the Doctor ever regenerated without trauma? Never, I think.

I know they film out of order, but it feels odd to know already what his outfit is going to look like. Here is one other possible minor spoiler: in the scenes filmed, the Sonic Screwdriver gets destroyed (and Matt Smith was slightly injured in the process). Between Matt Smith's age and that plot device, it's like Steven Moffat is trying to copy the Peter Davison era.