I haven't picked it up, but I recognise some of the titles - they're reprints from old issues of White Dwarf and Inferno! magazines, so you could probably Google them individually to find out what they're about.
The ones that I recognise are generally very good - The Wrath of Khârn is one that especially stands out as being memorable, as it details a fight between two Chaos factions (you don't need to take a wild running guess to figure who wins that one, but it's a good yarn none-the-less )
Many of the ones I don't recognise are newly released for this collection, so I can't comment on their quality. I'd imagine that they're comparative to the others