To start with Early's question about the Doctor's age, I think Matt's Doctor was slightly older than that to start with, but he also had some extended periods off-screen. I recall in one of his catch-ups with River he was quite a bit older than he'd been previously. I don't know how long he spent sulking after losing Amy and Rory, but as I remember his last story he actually spent many centuries of his time-line defending Trenzalore (even if it was a few minutes to us). So I think the 2,000 year figure could well add up, though I'd have guessed upper teens (centuries) myself
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As for the episode itself, as a story it didn't match The Eleventh Hour (Matt Smith's debut) IMO, but then the point was introducing the Doctor rather than the actual plot. It did introduce a couple of possible longer-term plot themes, and I'm actually more interested in whether they'll do anything with the Doctor's speculation about why he has that particular face than the one that's getting more comment.
I did find the writing a bit defensive in places. The companion is often supposed to embody audience's perspective, and here they were clearly worried about whether part of the audience will handle an older-looking Doctor. The problem I had with it from a dramatic point of view is that this is the one companion, apart from Susan, who should be least phased by what's happened, because she has seen all of the Doctor's past selves. But maybe she doesn't remember that very well, or maybe it's a different matter when it happens to "your" Doctor in front of you, so I'll give them a bye on that.
So, the Doctor himself. I'll take my impressions from the second half, after the manic/amnesiac phase was beginning to die down. I saw a more reflective, more self-critical Doctor there. He's literally been given a new start (a new regeneration cycle) and seems to be starting to question his life. Personally I'm fine with this: good as Tennent was, the thing I liked least about his Doctor was a tendency towards self-righteous certainty, so a Doctor who questions his own actions (including, if I caught one little aside right, his attitude to some of his companions) is one I'm happy to see. But he also has an acid tongue, a willingness to get physical, and more menace than either of his immediate predecessors could manage. Popping veins and bared teeth followed a few minutes later by a display of vulnerability. It remains to be seen where they'll take it, but I'm not worried about Peter's ability to handle the role.
Did love the expression on his face when the robot lowered the mirror, and you could briefly see that he'd been considering how his words applied to him as well as it. And the allusion to the end of "The World's End" (Eccleston's second episode) in the way the story finished.
