I finished watching Nu Who series 4 today. I have to admit that I really enjoyed this and am annoyed with myself that this was the point I stopped watching when it was screened on tv. Tate was excellent as Donna Noble and it was truly refreshing not to have a companion making puppy dog eyes at The Doctor all of the time (although this point was slightly over-played with the recurring joke "We're not together!" which got a bit tiresome, along with Tate's shouting and "I'm just a temp!" modesty). My usual gripes with RTD's stuff are still there but I especially liked the Ood and Sontaran episodes. In fact, this was the first series that didn't have an episode I didn't enjoy now that I think of it* Having already seen some of her in the eleventh Doctor's stories it was particularly odd to see River Song for the 'first' time. I pretty much met her half-way at the point she meets the Doctor I think, confusing the timelines even more
I'll be trying the specials soon although I do recall seeing some of those.
* edit: scrap that, I forgot about the series opener. The Adipose episode, that was bloody stupid. And that was actually the last episode I watched when the series originally aired