Right, I just played through the demo as Jotaro, and I'm amazed that I forgot just how much damn fun the game is.
First things first - the settings. As arit said, the menus are in English, as is everything else, so it must be set to your machine's language. Cool beans. Also, not only does it have "visual expression" (blood or sweat) settings, but also filter settings too, so if you don't like the "HD" filter, you can turn it off for good ol' retro-style pixel art gloriousness! Not that I had much of a problem with the filter, except for the jagged lines around sprites that appear sometimes.
Otherwise, you've got three rounds of Story Mode, with four characters to choose from: Jotaro, Avdol, Hol Horse (<3) and Dio. Control is smooth as silk, moves come out like butter, no execution barriers here. Graphics are fast, colourful and smooth too, no hitches, all cut scenes are in English, and loading times are mercifully short between matches. Good job, so far.
To the guy who said there was something wrong with the sound - nope, it sounds just like that in the Dreamcast version (I can't tell you about how it compares to the arcade original, for obvious reasons, but I expect it sounds the same, too).
No online multiplayer in the demo, though - booooooo. I can't say if the game has local multi or not - I only have one controller for PS3, sorry.
I dunno about twenty bucks worth, but it is a good version of JBA, I can say that. I'll probably end up getting it just because I'm a JoJo fanboy, myself.
Kaijima - sadly, no, but at least you don't have that smear filter anymore!