It's a follow-up to Red Dead Revolver, but the gameplay is totally different. This is more like a Grand Theft Auto in the old west. The co-op and multiplayer missions are another nicely added touch.
It doesn't have a spaghetti western soundtrack, but the soundtrack is definitely heavily influenced by Marricone, and it's pretty awesome in its own right. You can find the songs on youtube, just search "red dead redemption soundtrack"... great stuff!