Let's face it: the final season (#8) was one of the worst seasons in any show I've ever enjoyed (mostly, I've never found dry spells to last a whole season). But if you judge this show by the last season, of course it's going to come across as inferior. That is an entirely unfair assessment-- because "That '70s Show" was, in its day, a brilliant and hilarious sitcom about a bygone era and how the people who lived there weren't so different than we are here in modern times.
All right... ignoring Season 8.
Topher Grace stars as Eric Forman, a horny geek of a teenager with a perpetual love of Donna (Laura Prepon), the feminist girl next door. Playing their friends, Danny Masterson (Hyde), Mila Kunis (Jackie), Wilmer Valderrama (Fez) and even Ashton Kutcher (Kelso) give fantastic performances in (almost) every episode. The best one is probably Fez, a foreign exchange student who is as mentally promiscuous as they get. What country is he from? Try to figure it out! For another dimension of entertainment, Debra Jo Rupp and Kurtwood Smith are phenomenal as Eric's parents. Rupp, as Kitty, is both formidable and sweet, sort of like Mrs. Brady meets Marie Barone, while Smith's Red exists mainly to scare the pogees out of everyone. Don Stark and Tanya Roberts play very well opposite each other as Donna's parents, the chauvinistic but likable Bob and the airheaded Midge. Tommy Chong has occasional appearances as Leo, a stoner who acts as a father figure to Hyde.
Apart from the anachronistic errors that pop up quite frequently and the over-the-top lessons that sometimes come (and that deplorable final season), "'70s" is a terrific show with amazing writing, spot-on direction, and a feel-good vibe pulsing through every episode. They're all alright.