Nick Cave and Warren Ellis make beautiful, wonderfully haunting music and this double album is a perfect introduction to it.
It has a slightly limited appeal to die-hard fans, because they'll end up with a pretty much redundant disc 1 when the full soundtrack to The Road is released. For completists it's a must for the previously unreleased material, but as is often the case, you'll end up paying full whack for only a few tracks you haven't heard.
For me it's worth it because the music that Cave & Ellis create is so beautiful, and their output so lamentably small, that anything new is automatically a must-have.
In fact, I'd say to anyone less familiar with their work who buys this and falls in love with it, that the soundtracks to The Proposition, The Assassination of Jesse James (and no doubt The Road) are worth owning in their entirity. And while you're at it, you may as well get hold of everything by Dirty Three (Ellis with two others, but without Cave), which is very similar in style.
Personally, I'd also recommend everything by The Birthday Party, Cave & The Bad Seeds, Grinderman and the 'Death of Bunny Munro' audiobook soundtracked by Cave & Ellis as well, but maybe that's going to far. I'm reviewing one album and telling people to go out and buy dozens more. But in my opinion Cave is an awesome talent (he wrote the screenplay to The Proposition too), and Ellis is a wonderful composer and musician (and the main musical impetus for these soundtracks).
So yeah, musically five stars as always. Four simply for the fact that, as a fan, you always end up having to buy the same song twice. There's always iTunes I suppose...