I just picked up the game this weekend, and it's pretty freaking cool. I've been pleasantly surprised by it. I was kind of in the same situation as the one mentioned above--I was curious, I'm a fan of westerns, and I had been hearing a few positve aspects, so I decided to give it a try. I'm glad I did.
Bottom line, the gameplay is very good and very fun. It's got a pretty fast pace also, which makes it seem almost like an arcade game at times. I don't know if it's just the western theme to this game or the actual gameplay, but this game has me hooked.
IMO, this game has gotten a bit of a screw job in it's reviews. I've seen scores ranging from as low as 4 in EGM to as high as 7.9 (I beleive) at videogames.com. The 7.9 probably isn't too far off, but I still think it deserves a higher score.
And yes, the music is very good. Sorry, I don't know if one of the tunes you're talking about comes from another western, but in the game's manual, it's got a complete soundtrack listing which includes each song's writer. BTW, the manual's in full color and pretty stylish also. Overall, this game has very good, and entertaining, production values.
If you're at all interested in this game, definitely check it out, if not pick it up entirely--you won't be disappointed.