On the whole I was reasonably happy with Dr. Who
The plot had to be that Donna and the Doctor would get back together and fight some alien menace - there really wasn't any other way a reunion would work. The bit with them just missing each other at the start began well but went on too long, but once they finally met the chemistry seemed to work reasonably well.
The alien menace had to be the silliest ever, but really cute - I hope it turns out that some miss the mothership and move into the sewers eating people or something, because cute horrors are always fun.
And Rose! Her appearance makes absolutely no sense (if she's called in from another dimension why doesn't she go directly to the TARDIS), but it's nice to see her back. Now if they can only get Martha and Sarah Jane into an episode...