I thoroughly enjoyed it actually, which is really not the reaction I predicted from myself before watching it.
It took me a while to begin to enjoy it, I wasn't convinced by the beginning, it seemed to move too fast. From where Martha helped the Hath however it really drew me in.
What I liked most about this episode was the very different angle of the story to past ones brought out a very different side to each character. We see Martha sobbing her heart out for the poor Hath, Donna really in her element solving a lot of the mystery with her paper and pen and of course the Doctor. For the first time in the new series (1,2,3 and 4) we really see the Doctor's paternal side shine through aswell as the "fire and ice and rage" he is so famous for being.
I actually cried when the Doctor held the gun to the Captain's head. Never would you have thought that even over the "generated anomaly" that was his dead daughter that the Doctor would have done such a thing. It really gave the Doctor another side which was spectacular.
I did expect Jenny to regenerate, but was slightly surprised when she just woke up. Is that possible for a Time Lord? I'm not sure she will be in the final three episodes, but I am sure she will make another appearance. That episode opened up so many oppurtunities the DW team would be silly not to take them.
The Hath - I know Martha (I think) said they were part fish, part human, but they looked more like Brachiosauruses to me. (Sorry about the spelling) I really liked them, but they didn't seem to have quite enough personality to be memorable, unlike the gorgeous Ood.
I especially liked the twist aswell, with the war only having gone on for seven days. It was a real eye opener really as I'm guessing most of the audience thought, as I did, the war had gone on for years and years. It was really quite clever.
Overall, I really enjoyed it, but felt that Jenny could have been given a bit more personality. She really didn't stand out in my eyes.
This is one episode I can't wait to see again, just to experience David Tennant's stunning performance.