THis is maybe the 8th Trojan box set I've bought, and it's another quality collection. If you buy several of these there will be a small amount of overlap, but it's maybe 3-4 songs that appear elsewhere on other collections.
I'm not familiar with a lot of the non-reggae "hit" versions of these songs, but it's fun to hear some of the other ones that many people will recognize like Monkey Man or Red Red Wine. I'd say that the liner notes also get some points for subtlely (and not so subtlely) dissing UB40 in discussing their repeated success doing covers of other peoples' songs. But whatever, that's neither here not there.
This is another great collection of older 60s/70s reggae & rock steady. If that scratches your itch like it does mine, then this is a no brainer. From Trojan I'd also suggest any of the dub collections, Roots Reggae, Rare Groove, 12", Nyabinghi and The Aggrovators. Just great, great stuff all around.