Yes I believe so...It has the same general gameplay style and "feel" to it...but the environments in Anniversary are a bit more epic...especially in later stages...old school egyptian tombs, the roman colosseum, etc.
I'm not sure what you mean exactly by "more epic?"
The puzzles in Underworld were much better than Legend or Anniversary IMO. They really opened up the environments in Underworld, so that the puzzles and platforming aren't nearly as linear as they were in previous games. You really are exploring some huge environments, rather than being funneled down a path. Otherwise I agree, the games all have the same general style and feel. Anniversary is certainly worth $5 though.