The PS1 version of CvS takes a visual beating compared to the Dreamcast version (I only had the non-Pro version on DC), although one up-side as far as I'm concerned is that now the backgrounds are the same resolution as the characters--low. : P But of course the animation is choppier and the visual effects are less impressive; and one really curious thing is that the characters have checkerboard dithering patterns on them, in a lot of cases only when they're facing one direction. : o I guess this was a means to save bit depth and thus sprite size and thus RAM. Anyway is all together isn't terrible and isn't one of Capcom's worst PS1 ports; load times aren't even all that bad, and you can skip past the between-bout character quote and order setting screens entirely if you want, to save load time further.
I did have the thing crash on me when trying to run on a PS2 with the Fast Disc Speed setting, though! Playing Arcade mode with a two-character team, in one match I noticed a pretty significant pause before the game even started loading after one character was eliminated mid-match; and then, on another character elimination, the game just froze altogether. : P So no more Disc Speed alteration for this game! (My disc also stutters during the Capcom logo in the FMV intro; it doesn't appear to have any bad scratches on it (I got it used off eBay) and otherwise seems to work okay, so, I dunno.)
Pro adds funboy characters Dan Hibiki and Joe Higashi. There are also "EX" versions of the rest of the cast, which have slightly different move sets--you unlock them with points earned by playing the game, even in Practice mode (which some advise is the fastest way to do it). There are also big boss characters to unlock as level 4 characters--this game has a fixed ratio system where each character is worth 1 to 4 points, the higher point characters having more health and doing more damage than the lower point characters, but they are allocated by points in a match, so you can for instance have 4 1-point characters on your team, or 1 4-point character--or any combination in between. It's an interesting system, but it is a little limiting in terms of what characters you can or may want to select, especially since the professional analysis is I think that ratio 3 and 4 characters just aren't worth it.
I don't care about that, and, because the game doesn't have a random select, made a script to pick random teams : ) : http://smbhax.com/cgi-bin/teams/cvs.pl
Oh! Also there's a PAIR MATCH mode which plays like Arcade mode I think except that you can pick ANY two characters, so I guess that gets around the ratio system limiting match-ups problem, if you'd call it that. I actually kind of like the quirkiness of the fixed character ratios, although it is nice that in the sequel, they freed up ratio selection entirely (only a max of 3 characters per team in CvS2, though).
The difficulty is a bit on the easy side--I beat it on level 5 (of 8) on the first try, for instance. Hopefully the remaining difficulty levels stiffen up a bit.
You could say that there's a rather surprising lack of gameplay modes, because ARCADE and PAIR MATCH is it, eh aside from regular player-vs-player VERSUS, I assume. There is no Vs. CPU, or even Survival.
So, the PS1 version is a mixed bag, but I do kind of like it for its quirkiness, and also that the boss--since you do have to play an Arcade structure in single-player--isn't ridiculously harder than the rest of the matches.