Things I didn't like:
-From the last few minutes, the new doctor. Maybe I'm still sore over losing Tennant and I'm sure I'll warm up to him during S5, but his role in this episode didn't convince me at all. I trust Moffat to make this work though.
-Martha/Mickey being married. It was random and unnecessary. Small nitpick though.
-The fact that we didn't find out who the woman was in the episode, we had to find out through commentary. That's just dumb.
-The gun scene. Recocking the gun every time he switched between the Master and Dalton

Just bad.
-Everything over the past two+ hours was solved by simply shooting a machine. Really?
Things I liked:
- John Simm and David Tennant - both were great, as usual and pretty much made the episode enjoyable
-Timothy Dalton - He was cheesy and totally hamming it up, but this is Who and therefore perfectly acceptable. He obviously had fun with the role and it was just as fun to watch.
- The true meaning of "he will knock four times." Not what I expected.
- Most of the last 20 minutes. Was having the Doctor visiting all his companions cheesy? Yes. Did I enjoy it regardless? Sure. It was infinitely better than the S4 finale, shoving them all into the plot. A couple of minutes of closure per companion was nice. It really shows that this is the end of an era and the show is going through a reboot of sorts.
- Donna. Fuck the haters, I like her.
-The Doctor's final words.