Planet Of The Dead is a bit of a weird one for me.
On the one hand, it certainly is nowhere near the high quality of the episodes in the second half of Series 4. It's quite a lightweight story really where style definitely wins out over substance. The Dubai setting definitely gives it a glossy feel but the story itself is not one that springs to mind when thinking of the classics of the Tennant Era.
On the other, though, is that unlike the other specials, The Tenth Doctor is at least behaving normally and is not the grim shadow of himself that he became later on. Here he's having fun and even though the flying bus is a bit far fetched The Doctor is at least enjoying himself in the meantime.
As for Lady Christina, I liked the way Michelle Ryan portrayed her. I think it's good for her that this was another chance to pull away from Zoe Slater in Eastenders and I would like to think in another time and place she could have been a proper companion. I liked the banter between her and The Doctor.
As for Malcolm, I thought he was superb! He didn't annoy me at all and I thought he was one of the best things about the story.
Unlike others, I actually prefer this to The Waters Of Mars as it was more playful and fun and not so downbeat and grim.
However, it's not perfect by any means and maybe if it had been part of a proper Series it may have worked better.