3rd Strike is the most polished, cohesive SF game ever, imo. By cohesive, I mean it doesn't just feel like they imported a bunch of different 2d character art from other Capcom games (because they didn't); everything is quite well put together, rather artistically. Also, I continue to be very impressed by the soundtrack, which has always been a favorite part of SF for me. I love how the music changes to a different verse each round.
The SF2 game itself (is it just called anniversary edition? I can't remember...) is OK, but to me it's more fun for nostalgia than for actually playing. There's some definite balance issues, and unless you're the hardest of hardcore, why bother playing SF2 Ryu versus SSF2T anyone else? The movie's a nice touch, but I've never watched it to completion.
In short, I'd say it's worth picking up, especially if you have pals around to play it with. Personally I don't find the lack of online in the PS2 version to be too big an issue, since I still have nightmares of playing CvS2 with the Xbox pad...but I'm sure that's a minority view.