This is quite late after the release, the reason being I saw the film for the first time this month and took to the soundtrack like so many others. I immediately discovered that there were 2 volumes. Did anyone else? There are no reviews on this so..... It makes me a bit cynical about why it was released in 2 volumes rather than one compilation so it loses half a star rating for that alone. Then apart from the fact that some of the tracks are excellent (Lynsey Buckingham's "Big Love" was spine tingling, especially as it is a live version), why, pray tell, did they stick one track on that was never in the movie? "Lovo" by Pinback does not add anything to the feel of this soundtrack. There is also a different version of "Jesus was a Crossmaker", but that's ok, as it is a good version.
Anyway, that aside, it does have that road movie feel, or even "Sunday spent hanging round the house cooking dinner and reading the papers feel".
You may already have the odd track in your collection,so it's up to you, but I would think it is worth it if you liked the songs you heard during the movie, (if you could pick it up cheap maybe).
My last comment is that there are still songs missing from both volumes, like U2's "Pride (In the Name of Love)", presumably they could not get permission for it.