I am completely without an opinion; I don't know the actor well enough (I vaguely knew his face). But Steven Moffat has written some of the best episodes of the last few years so I think it's safe to trust him on this.
I think the only important thing was to avoid a David Tennant clone, and they've done that.
I was personally hoping for Patterson Joseph, just because he's been great in every role I've seen him play. But there are lots of great actors...
---
"The crows maintain that a single crow could destroy heaven. This is beyond doubt, but proves nothing against heaven, since heaven means, precisely, the impossibility of crows."
-- Kafka
