I have been a fan of Calexico's work since Spoke was released in the mid-90s. They've worked through a variety of sounds over the years, and this album seems to begin a new chapter in their work. As has been mentioned in reviews elsewhere (e.g. Pitchfork), this album is their most straightforward and may well be accessible to listeners not specifically interested in the Morricone-esque soundscapes they crafted on previous albums.
I think the earnestness of Garden Ruin suits Calexico. Mind you, I really enjoy the sparse desert feel of their previous work, but most of the songs here would feel natural placed next to songs by Wilco on a playlist. I find myself humming along to a few of them walking down the street (Ipod or no). Traces of their earlier sound are present here -- especially on the (mostly) quiet and still song "Smash". This album, as with all other Calexico works, would be a good choice to bring a road trip.
Of particular interest -- I feel -- is the final song of the album, "All Systems Red". I've been struck by this song since first hearing it live a few months ago on the tour with Iron & Wine. The song, to me, seems to be about deciding whether it is possible any longer to maintain one's faith in the ideals of America. The song gives me that feel of immediate importance that songs by U2 once did. I had no idea that Calexico had this in them. I don't know if future work by them will be more or less political in nature, but if they can occupy again the same aesthetic space that lead to this song, I would be very happy to hear it.