I love that The Avengers can be watched totally at random and in any order, so that's basically what I've been doing. I estimate that at this point I've seen a little less than half the series. The show's a lot of fun and in many ways the coolest thing on TV in the 1960s, but I tend to take it slow because the episodes are so full of weird turns of events, double-crosses and totally off-the-wall twists that are hard to make sense of, and the seeming randomness of events paradoxically tends to make the episodes run together sometimes, from my perspective. Essentially, while there are obvious standout episodes, I have trouble following the train of the plot sometimes and so it all becomes a lot of zany, memorable set-pieces. This is particularly true of the later seasons when The Avengers stopped being a "crime" type show and turned into total chaos.
I must say the big surprise for me in this one was Donald Sutherland. The Avengers keeps throwing casting surprises at me, in fact, and it's pretty cool. Here, Donald's character is working alongside John Hollis's foreign agent (I don't think his name or country of origin is ever even mentiond, although I might have missed it) to test soldiers (or something). Yes, to be honest, I'm really not sure why any of this is happening, or who's responsible. But the setting was cool, the banter between the bemused partygoers hugely entertaining, the cast first-rate, the music cool-as-hell, and John Steed was a total boss as usual. Everyone gets on a plane to attend a mysterious party, and even when they realise nobody knows what the hell is going on, they still keep drinking champagne and chatting and smoking like well-behaved gentlemen. Of course, the characters show a lot of eccentricities and that's one of the biggest charms of the show in general.
eventually it turns into a bizarre kind of And Then There Were None.... type scenario as many of the characters get bumped off by an unknown killer whom it's indefatigably stated is one of them! Interestingly, and again somewhat par for the course for this show, it's the women who kind of end up saving the day. Emma Peel isn't in this one much at all, so you know she's going to show up at the end to kick some arse, and she does. She's got Steed's back, always, just as he has hers when she has her few solo adventures, and Diana Rigg is just amazingly cool -- just too cool for words in this role, really.
I like to watch this show late at night, sometimes after having had a few drinks. It works well and suits the mood, but sometimes I'm not so sure it helps me figure out exactly what the devil's going on. Then again, The Avengers is just the kind of show you have to "roll with" and just let all the suaveness and coolness happen around you. I'm sorry if that all sounds half-arsed or something, but it's really the best way I've found to go about it. It's not that you have to switch your brain off, exactly, but that the show's writers (and performers) were just totally on their own track and good luck trying to figure anything out before it happens. Even the endings of most episodes leave me wondering "wtf was all that about?!' some of the time. But there are usually clues in the dialogue, which are just really understated and not made a big deal of. The "big deal" is all about the style, the laid-back nature of the character interactions even when they're at odds, the drinks, nice cars, weird gadgets, sudden and sometimes hilarious death scenes and, in this season, the brilliant interplay between Rigg and Mcnee.