Let's start with the good. You get an awful lot of tracks for a limited amount of dosh. This collection is really good for creating or adding to a chillout playlist. However, be prepared to end up with just a quarter or so being good enough to save.
Personally, I found far too many tracks were either not the original singles or, worse, had been ruined by the producer's arrogant assumption that all good songs can be improved by changing the tempo, the beat, the rhythm or whatever. Consequently classics such as At Last by Nina Simone have been absolutely adulterated. With a compilation album one has come to expect a different version than, say, the radio edit, but this collection just went too far off-road for my taste.
The 5 individual CDs are arranged into genres. CD5 - a classical/TV adverts collection was my favourite. I don't really know what genre to place CD1 in - maybe "tracks you have never heard of but might like" .... or not!
Fortunately, there were still enough good tracks over the whole collection to warrant giving it a three star rating.