42 has a feel similar to Impossible Planet and Satan pit, which are some of my favorites, and it's got a literal ticking clock that makes everything so imperative. And the neat creature being a living sun, how cool is that? Super-cool, that's how cool!
The Human Nature / Family of Blood double feature is just great-- MyFutureHusbandDavidTennant gets to act differently, and gets to comment on the type of person the Doctor is, and since I'm a huge fan of metafiction, these eps are just great fun. He's so very ordinary as John Smith, so distressingly normal and boring and so very well integrated that he does and says things that are not in the Doctor: he lets the one kid beat the other, he teaches children to kill, he tells Martha to keep her place... and he's so useless in an emergency situation.
And there's so much screaming in these episodes. So much screaming. It made it hard to watch the first time around, being so in love with the joyful!Doctor we've seen through the first two seasons, but this time around, the sobbing emotional breakdown of John Smith was almost worse to watch. It's so unlike the Doctor, so raw and human and hopeless... And then there's that miraculaous and perfectly smooth transition from the helpless John Smith to the wonderful restored Doctor, that has just a little bit of mixed feeling-- we're glad to see the Doctor back, but at the same time, we're sad to see John go and so proud that he gave himself up so the Doctor could save everyone.
The Doctor was so dark in season three. Always walking into sure death, always burning things up and yelling and screaming and critisizing. Always being hurt. Always being half suicidal. But in these three episodes, we can see him being the best that he can be, even with all that brokenness.