It seems the big rail splitter among Red Dwarf fans is whether Series I & II were the show at its best or an incredibly awkward developing period. I'm in the former camp. I find something charming & homey about the production design. Norman Lovett was a way better Holly than Hattie Hayridge. And I agree that, once Kryten joined the regular cast, the plots became too random. I like that early claustrophobia; that it's just these 2 guys who hate each other trying to stave off boredom.
Series III was an awkward transition year. They changed the production design but weren't yet able to make it look good. Rimmer & Lister's quarters look too white & sterile. There are some good episodes here, like "Marooned" & "Polymorph." But "Backwards" never really rises above its backwards gimmick. "Body Swap" is one of the worst episodes the show ever did. Sadly, I attribute that to Craig Charles being a very limited actor. Chris Barrie, as a seasoned impressionist, is acting his ass off to be a convincing Lister. Craig Charles is a crap Rimmer.
Series IV-VI were a marked improvement. It's a different show from Series I & II but there's a lot of great episodes here, especially "Meltdown," "The Inquisitor," & "Gunmen of the Apocalypse." Only one real misfire here-- "Terrorform." It's a fun idea, modeling a planet after Rimmer's psyche, but the ending is too cliched & predictable.
Series VII struggled from the lack of a studio audience, the departure of Rob Grant, & the departure of Rimmer. There's not a whole lot to love here. The highlights: "Stoke Me a Clipper," "Duct Soup," & the Arnold Rimmer Experience from "Blue." "Tikka to Ride" has a funny concept with its take on the Kennedy assassination but never congeals as a great episode. "Beyond a Joke" totally sucks (except for Kryten bringing a tank into Jane Austen world).
Series VIII was a very good revamp of the series concept. I liked the idea of bringing back the Red Dwarf crew. Even more, I loved how the show reinvested its focus on the Rimmer/Lister relationship. "Back in the Red," "Cassandra," & "Krytie TV" are all excellent. "Pete" feels padded, because it was. "Only the Good..." has a great ending and a few funny bits. ("Have a fantastic period." Cat picking a fight in the cafeteria.) But too much of "Only the Good..." feels more like a bunch of unrelated sketches lumped together.