I've also got the 1980s revival series on DVD. Despite some 80s cheese, it's a reasonably satisfying continuation. Peter Graves is there, leading a new younger cast (including Gregg Morris' son!).
I watched the first episode on YouTube, and you know, even though as you say it's pure cheese, I found it pretty good 80's action fun.
It also shows how good an actor John DeLancie really is, with Q it's effectively easy to be a scene stealer, but here he was playing a part that was much more generically written than even the worst Q episode but he still managed to run off with the entire episode and did a hell of a lot with every arched eyebrow.
Also, considering it was a clearly cheap American show filmed in Australia, it actually didn't do too badly at faking central London, especially if you allow them not cutting down every palm tree in the city they filmed in just for one episode. I think DeLancie may well have been the first character in an American show to go into a "London" phonebox that isn't one of the old big red ones, it even looked as if it had the right BT logo for the time on it (though of course, there are red phone boxes and black cabs and red buses everywhere else, but that is London for you).
The main failure was having every other extra carry a big John Steed umbrella despite the great (almost Australian) weather London seems to be having and even if they're wearing a denim jacket and a baseball cap.
On the regular series: I thought the first two parter was a bit drawn out myself, with less endless shots of the female guest agent of the week twirling about on her trapeze in a skimpy costume they could have probably done it in an hour.
Fantastically poor doubling for Landau when he's trying to escape from the prison made up for it though.
Just watched the Ransom episode, a nice tense variation from the formula that felt like Hill had found his groove a bit more. Nice to see Mr. Lesley on the team as well (I think he was also in the pilot), doing some fantastic non-speaking extra emphatic nodding.
I think, allowing that I don't think they let you have a good look at his Briggs face in the first episode (and he still had Landau's voice in his brief speaking bit) that this was the first time the man of a 1000 faces has successfully impersonated a real person who isn't someone who by amazing coincidence looks like Martin Landau in a wig and make up.