The stories contained in this volume are much more meaningful if you’ve already read at least the first book of the series, Throne of Glass. They fill in details referenced in Throne of Glass about Celaena’s background, and how exactly she came to be in the position she’s in at the start of that book, but they have more impact if you already know Celaena. If this was your first outing with her, you probably wouldn’t get to know her well. Each story is connected and leads fairly logically from the previous one, though it doesn’t quite have the cohesive feel of being a novel — it’s definitely episodic.
If you enjoy Celaena, it’s worth picking up; it fleshes out details about her past and gives more weight and meaning to some of the things she says and does in Throne of Glass. It’s an easy read, too; for all that it’s 450 pages worth of storytelling, it seems to fly by.
The books themselves… I’ve never been quite as in love with them as a lot of YA bloggers are, or were, so the collection remains exactly what I expect of Maas: an entertaining story (or in this case, set of linked stories), with an engaging but not perfect female character. (Come on, though; Celaena’s a highly trained assassin, yet she trusts the wrong people, she can be spoilt and petulant, etc. Sam Cortland, I think you deserved better.)