I’m not sure how I feel about this casting. On one hand it’s nice to see an established actor have the roll. It might bring a darker, more mature Doctor than before. On the other hand, I think he might be a touch too old. But, like I did with Matt Smith, I’m going to give him a chance to grow into the role and see what happens.
I don’t think it’s fair for any of us to pan his ability to be The Doctor without seeing how he does first. He may surprise us with a very complex, and intriguing portrayal as Smith did.
It will be interesting to see how things turn out, but I’ll tell you one thing: I’m betting the regeneration is during the 50th anniversary special. Why? Because there’s something River said the Clara and The Doctor. To enter your own time stream is fatal, that the winds of the vortex would tear you apart. Ok, so where’s the Doctor? Inside his own time stream. How will he get out if it’s fatal? Sounds like a regeneration to me.
Always pay attention to the words spoken during a Moffatt episode. He writes from the back to the front, so a lot of them foreshadow the climatic episode.
Talia's World 
It’s definitely strange to think of an older actor in the new series, given the relative youth of the three we’ve had already. But I’m personally glad we have an older Doctor, and I think he’ll be fantastic in the role.
I’m actually intrigued by the casting. It shall be interesting to see how he puts his own touch on the role.
I might go back to watching it. I got a bit bored of the young guys. Taking it back to it’s roots. As a kid I am not sure what scared me most Tom Baker or the Dalaks! Lets not forget the first three doctors where older…
Tom Baker definitely could be over the top a bit. I, too, think an older doctor is in order…especially given the dark and mildly sadistic person he’s started to become. That requires an older actor to pull off. I’ve always laughed at the Daleks..it’s a toilet plunger and an egg beater with delusions of grandeur! They do tickle me and I see where Rick Berman combined them with the Cybermen to make the Borg in ST TNG.
I will say, I’ll miss David’s interaction with Lumic in ‘The Age Of Steel.’ I just loved how he channeled the third doctor-with bits of the second and fourth-in there. Most of that scene-esp when Mickie was looking up the code to the emotional inhibitor-was third doctor all the way. It was fun to watch!
Matter of fact, I might have to pull that up on Netflix and watch the scene again now that I’ve mentioned it.