The first disc is a remaster of the album proper. Apparently, this is different to the LC remaster from 4 or 5 years ago. I've not had the opportunity to listen to it on a decent hi-fi yet so can't comment but it is suppose to be an improvement over the last release.
The vanilla tapes are an interesting curiosity but how often I'd go back to them, I don't know. The tracks have been available before in bootleg format ; this is the first official release.
The DVD is 30 minutes long and an interesting watch. It confirms Guy Stevens was an absolute nut at any rate. There's 3 promo videos on their too, but I've not watched them so no idea what they are.
If you're a massive Clash fan get it. If not stick with your original version.