Of all of the Doctors in the classic series of Who, I have always felt that Colin Baker (as the Sixth Doctor) got way too short a season. Much of it was due to the infamous 1985 "hiatus"...and when Who returned, it was a limited series (14 episodes of 25 minutes each) with the overarching theme of the Doctor being "on trial".
Having rewatched the entire Trial of a Time Lord on DVD (with an excellent documentary, Trials and Tribulations focusing on Baker's time in the role, and about which more later, if that makes sense), it's easy for me to say that 2/3 of the story works....with the other third slightly saggy.
The premise is relatively simple (at least, in Who terms) - the Doctor is pulled out of time and space, and is put on trial for intervening. (Which begs the question - wasn't the ten part War Games, coming soon to DVD in November, supposed to have answered that question). In short, the Doctor and his prosecutor, the Valeyard, use evidence from the Doctor's past, present, and future to prove his innocence...or guilt.
The first four episodes, written by Robert Holmes, are the strongest in the entire series - granted, it comes towards the end of his writing career (Mr. Holmes passed away during the making of this story), and it's no Talons of Weng-Chiang/Spearhead from Space/Insert favorite Robert Holmes story here, but it sets up the initial conflict - not only is the Doctor on trial, but there seems to be some "tampering" with the evidence, and what at first seems like an innocent trip for the Doctor and Peri turns out to have more sinister implications...and it also shows that the hiatus may have helped Colin Baker tone down some of the more, er, obnoxious aspects of his Doctor.
(And as an aside - I'm a Robert Holmes fanboy. I only wish that I had sent him a fan letter earlier - never got up the courage to do so, and once I did, found out he had passed).
Phillip Martin's episodes (four through eight of the story) are a rather strong mix as well. Of course, it doesn't help that it has Brian Blessed. That's what we need more of in our entertainment - Brian Blessed So awesome, his name must be in bold. The rest of the story is enjoyable, only because we get glimpses of the Doctor acting very un-Doctor-ish.
And Nicola Bryant's departure as Peri? I have....mixed feelings. On the one hand, I see where it's used as a dramatic device (especially since the Doctor is pulled out of the story as his "present"). However, there is a slight whiff of "women in refrigerators" about it. However, this ending will, sadly, be retconned...
...and then, there's parts 9 through 12, by Pip and Jane Baker. It's easy to mock them - they're not quite fan favorite writers. And this is, quite easily, the weakest of the longer stories in this arc. However, here's my argument - if Pip & Jane were writing for a nice, adolescent-themed adventure series (kind of like an Afterschool Special), they would hit the perfect tone. Unfortunately, that tone - in Doctor Who - doesn't quite mesh (which is why I'm not a big fan of Mark of the Rani).
This was a year that saw the departure of script editor Eric Saward, and much of the DVD supporting material around episodes 13 and 14 discusses the backstory (as well as Saward's commentaries for episodes 1 and 13). The final disc of the four-disc set goes into detail - maybe way too much detail - about the controversies around the ending episodes. But what's more revealing is that, in interviews with the BBC's powers that be at the time (including Michael Grade), that they weren't quite sure what to do with a series that....seemingly, they did not enjoy. (One former BBC head of serials gets called out by another for not "supporting" the series due to dislike; footage of Michael Grade shows him to be rather contemptuous of Who fans). And given that episode 13 was half finished when Robert Holmes passed - and Pip & Jane did as good a job "finishing" the story in episode 14 - it's surprising that the entire story holds up.
However, this is a story that is worth watching in parts - Disc 1 (Holmes) and Disc 2 (Martin) are well worth watching; you can pretty much skip Disc 3 (Pip & Jane), but for drama both onscreen and offscreen - as well as a critical perspective on this time - Disc 4 is mandatory.