1)"Sontarans created by Robert Holmes" - Good to see the Sontarans, one of my favorites heels from the old show. I think they did a good job re-imagining them, although I'm not sure why felt a need to dress them in blue rather than in black. I liked Ross' description of them as a "talking baked potato". Lots of references to previous Sontaran stories here, including the line about females having weak thoraxes, and the gag about the proper pronunciation of "Sontaran". Good to see Christopher Ryan return to the show, he did a good job as Staal, The guy who played Skorr did a good job, too. Of course, when they started chanting "Sontar-ha!" I pictured Arhcie Bunker as a Sontarna, going "Sontar-hanh?" I liked Staal's jealousy about the Time War: "The finest war in history and we weren't allowed to be part of it." I see the war with the Rutans is still gong on - they ought to bring the Rutans back at some point, too. There's noting I like more than a shape-changing alien that looks like a phlegm ball. "We are the first Sontarans in history to capture a TARDIS." Umm, you did occupy Gallifrey at one point, doesn't that count?
2)Tennant had some good moments in this - I particularly liked the scenes between him and Wilf, and the moment when he got all snotty about being stuck on Earth. I thought he was badly written in his scenes dealing with Mace. It's fine for him to be anti-violence, but it seemd out of character for him to be such a jackass about it. I did like how the Colonel stood up to him and didn't take any crap from him.
3)Donna had some good moments in this, too. I liked the scene of her piloting the TARDIS, and how she was the one to figure out what was going on at the plant. The "I'm not coming with you"scene was pretty funny, too. I thought it was good how the "Here's your key to the TARDIS" moment was played as a "non-event". Donna had some good moments with Wilf as well - you get a real sense of affection between the two of them.
4)"Doctor? It's Martha - and I'm beringing you back to Earth!" Good to Martha again. I liked the interplay between her and Donna, and how she warned Donna about the consequences that knowing the Doctor could have for her family. Some good moments between Martha and her close - I liked that the Doctor saw right through the clone. "That Tom Milligan" - so Martha's engaged? Hmm...
5)The kid who played Luke Rattigan did his job well - you wanted to punch him in the face about five minutes in - of course, I can sympathize with his poor social skills, we geniuses often have that problem. I liked the scene where he and the Doctor correct each other's English. Still, in the end, the little bugger redeems himself.
6)I see they're now calling UNIT the "Unified Intelligence Taskforce" - apparently, the UN had nothing better to worry about. "Technically speaking, you're still on staff." Not that they ever paid him, of course. "Back in the 70's - or was it the 80's?" Nice nod to the infamous "UNIT dating controversy". I liked the mention of the Brigadier, as well.
7)Ah, poor Ross - you know when Doctor Who takes the time to develop a secondary character like that, there's a good shot they're going to kill him off. "Don't call Ross a 'grunt'. He's nice - we like Ross."
9)Some fun quotes:
Overall: A nice two-parter with some good character development and the return of a classic enemy.
[Part of list of Doctor Who episodes here.]