I have to say, after Dimensions In Time I've always been nervous about charity special episodes of Doctor Who, but this one was a bit special. The first meeting of an Old Doctor with a New One, and done in style with just the right amount of self deprecation.
Now this won't win Steven Moffatt a Hugo Award, but his mantlepiece must be getting a little crowded by now, but it was well written. A nice balance of outright comedy (it was a night of fundraising fun after all) for the casual viewer and in jokes and continuity references for the hard core fan.
From the moment Davison appeared, you could see from the beam on Tennant's face that this wasn't just another day at the office, this was a man being paid to work with a childhood hero, who looked just as much the Doctor now as he did back in 1981, OK a little bit saggy, but amazing that at 56 Peter Davison is actually older that William Hartnell was when he first played the crotchety old man.
The two styles of the Doctors from different eras was well captured and separated with the "cool" Ten hamming it up against the more "reserved" Five. A surprising amount of Doctor Who legend was crammed into the 8 minutes, and some Douglas Adams to boot, this was a thoroughly enjoyable romp.
Not only was it enjoyable, it took the highest viewing figures for the whole Children in Need night - great chap, both of him.