REVOLVER is a lot of fun if you're a hardcore fan of the Spaghetti Western. It's more of a Spaghetti Western than REDEMPTION (even using actual soundtracks from famous Spaghetti Westerns!), but...
REVOLVER's graphics are very very basic. I enjoyed that aspect -- especially since I knew the game originally was born of Capcom for the arcade -- but many look at it and say "that's stupid and cartoony!" For me, the graphics really went well with the spirit of the Spaghetti Western... especially the goofier movies like SABATA 1, 2, 3. If you're looking for realism, don't bother. You'd do better to play the JUAREZ games.
REVOLVER's gameplay also is a little awkward and strictly on rails. Like I said, originally it was supposed to be an arcade game with gun controllers, so it plays fast and loud but doesn't respond great using the PS2 controls.
I thought the voice acting and characters were great... and some hilarious (in a good way!).
I'd buy it again (it's pretty cheap)... but then I try to buy all Western games.