The Brain of Morbius is awfully good, considering. OK, you have to suspend your disbelief a bit because of the unlikelihood of Solon setting up his lab on precisely the same planet as the Sisterhood of Karn, and there's a wee bit of time-wasting running around in the second half of the story. But basically this is Hinchcliffe/Holmes Who at its peak, witty, gruesome (but not too gruesome), and also rooted in continuity without being wedded to it. I loved it.
I was surprised that I did not really enjoy The Pirate Planet very much on watching it again (for the first time since 1978). Not a lot of it makes sense, and it isn't really funny enough to compensate. Mary Tamm rather glows as Romana, and that is surprisingly the best thing I can find to say about it.
I was surprised that I did enjoy Warrior's Gate. A somewhat surreal plot line, with reflections on colonialism, empire and slavery, and also Romana's extended farewell to the Tardis (for once, decently signalled in advance, more perhaps than for any companion since Victoria). Even Adric, for once, seemed to fit in reasonably well. Definitely worth watching again.
I'm afraid Arc of Infinity on the whole left me cold; Gallifrey has become just a really stupid place, where they put Colin Baker, of all people, in charge of security. The moments of Omega's return at the end would have been quite effective if it hadn't been for the nonsense of the previous three episodes.
Given the current return of the Sontarans to our screens, I thought I should revisit The Two Doctors, which didn't impress me much at the time and which fandom has since excoriated. Actually, I liked it more than I expected. If you've only seen Troughton in The Three Doctors, The Krotons and The Five Doctors (as was the case for me first time round) it doesn't make a lot of sense; but the character here is rather more consonant with the actual Doctor of the later Troughton era - think especially of The Seeds of Death where he blows the hell out of every Ice Warrior he meets. Colin Baker seems unusually at ease with himself as well, and Nicola Bryant's skimpy costume makes up for Peri's rather whiny characterisation. Even Fraser Hines manages to invest Jamie with a certain maturity. OK, the story rather runs out of steam in the last of the (double-length) episodes, but Robert Shearman makes a good argument in About Time VI as to why this is happening. This is probably the Sontarans' least impressive outing.
Time and the Rani is, unfortunately, just dire. It's not the fault of the actors - McCoy does rather well in his first outing, and the others do their best with what they are given. It's a combination of the script, which is pretty run-of-the-mill, and the incidental music, which is just simply awful - I think the worst I can remember. (It's ironic that the music was the one aspect of NuWho that McCoy didn't like.) The wriring was obviously on the wall, and as ever with this period of Doctor Who I find myself marvelling that it lasted until 1989.
So, in summary, The Brain of Morbius and Warrior's Gate are real classics, and The Two Doctors held up better than I had expected; skip the rest.