I voted 'It wasn't bad, but wasn't that good either' and then saw that most here agree.
I grew up with a first-generation Trekkie and so know more about the original series than I usually care to admit.
I got the archons/Landru/'you're not of the body' thing. Captain Kirk/William Shatner is unfairly criticised: he was great in TOS and was a respected stage actor (Shakespeare at Stratford, Broadway... probably where the famous Shatnerian diction comes from) before 'joining Starfleet'. Handsome, the all-American hero (not bad for a Canadian): it worked. He didn't get too hammy until the movies (most of which were stupid IMO) IIRC. The brilliant, restrained, conflicted Mr Spock is one of the greatest TV characters invented. And Nurse Chapel was hot (which was of more interest to me than the ray-gun or philosophical stuff).
There were a few good stories. Roddenberry wasn't trying to create real science fiction (but had a couple of talented writers) but used the aliens-and-ray guns stories to make points about present-day (1960s) society and politics: 'A Private Little War' was really about Vietnam for example. He reckoned if he wrapped it up in the trappings of kiddie sci-fi he could get away with it. That said as I grew up I went off it when I realised, as a magazine article pointed out, that the 'good guys', the Federation, were really totalitarians, as shown by Kirk violating 'the Prime Directive' of non-interference when he ran across an 'alien' culture he didn't like, spreading the American, erm, Federation way. The Federation was obviously 1960s America, the Enterprise
its military. Oh, and the fact that most of the 'aliens' looked suspiciously human and spoke perfect English (sure, the 'universal translator'... shyeah, right... you've never met these people before; the gizmo won't work!) got to me.
'TNG' was pretty well done, nice effects, some good stories and some likeable and even world-class actors, and the Kirkian approach was ditched in favour of the Prime Directive. This Federation was more like the EU or UN with some teeth than the US. Riker seemed like the executive officer (deputy captain... 'Number One' comes from the British Navy; Roddenberry loved the Hornblower stories of C.S. Forester) of a real Navy ship, the tough disciplinarian doing the captain's dirty work in that department. Gates McFadden reminded me of an old girlfriend.
Big step up: having an actual international cast (thanks to better transport and a bigger budget?) not just North Americans doing vaudeville-like stage accents ('Kyeptin!' or 'Ye canna break the laws of physics'). But the human, English-speaking aliens were still a problem. From here on they usually had foam rubber glued to their foreheads, a go at realism I imagine. Worf was kind of a cutout ('A warrior
' blah blah blah).
'DS9' had potential, like the bar scene in Star Wars
as a whole series, rough and un-'Trek'-like. But I think it went downhill into 'space opera' and typical Trekness. Didn't watch much of it. Terry Farrell was lovely; Nana Visitor wasn't bad either. RenÃƒÂ© Auberjonois as Odo the shape-shifter was a nice touch. I liked the one where Quark and his nephew were the Roswell aliens and the implanted translator gizmos in them didn't work so the Army people and we were totally lost hearing them speak Ferengi.
The Maquis were cool: the libertarians of this allegory, pointing out that the Federation weren't necessarily the good guys. (That and Michelle Forbes was a knockout.)
'Voyager', from what little I saw of it, had as a cartoonist said plots that were a cross between 'Battlestar Galactica' and 'Gilligan's Island'. Expected Kate Mulgrew at any time to whip out a captain's hat and whomp the blond guy, Paris, with it. Couldn't buy into the black Vulcan ('the brother from another planet', 'Tuvok Shakur'): I think the Vulcans and Romulans - who are cool - are supposed to be based on the Japanese. The holographic doctor (with a 'tude!) was a nice touch and Kes was adorable. Liked how her character ended up, kind of apotheosised. I understood Jeri Ryan's appeal but didn't feel that way.
'Enterprise' had some potential but as far as I could tell from what little I saw it was typical 'TNG'-ish cash-cow stuff. Didn't look retro. Liked having Hoshi, a linguist, in the crew, finally acknowledging that they are trying to talk to aliens
. Jolene Blalock as a sex symbol was overrated.
Roddenberry was militantly anti-religious but I understand that changed in the shows after he died: the Bajorans' (Michelle Forbes' people) faith got some respect for example.