Plot - People are always saying this: "it's a dark film". It's got all the same bad stuff that happened in the first film, like arm mutilation and stuff, except now it's happening to the main characters more.
Form - Probably better than the first one.
F/X - Probably better than the first one.
Acting - More pulp stuff.
Mise en scene - Definitely better than the first one. Hoth and Dagobah are definitely the most compelling science fiction worlds on film.
Quotables - Countless.
Cool stuff - Everything.