I will say that there is a huge cast of secondary characters who appear and disappear at various places in the narrative. And I don't mind confessing that I sometimes got a bit muddled between them. Perhaps some of these could be better or more trenchantly described on their first showing to make recall easier. My mind was ejected from the narrative a few times because of this.
Otherwise, though, ''The Vanguard'' is a thoroughly enjoyable read. I loved the worldbuilding of a post-flood city filled with toxic waters and people living in, under and above previous landmark buildings. Sorcha and her band of friends lead colourful lives on the edges of legality and respectability and these are vividly described. I loved their wild, yet strangely practical, ways. It's not easy to survive in a post-apocalytpic world, but these guys are making a great - and very entertaining - fist of it. And then there's the reluctant super-hero plot. This is well thought through and straddles the boundary between fantasy and science fiction extremely well. Without dropping spoilers - I hate spoilers - the denouement is great. I wondered how Griffin would manage the lead-in to further books in the series and I really wasn't expecting it to go the way it did. So kudos to her for not being predictable.
I also enjoyed the dry wit that infuses this entire novel. Sorcha in particular has a mordant sense of humour and she offers many wonderfully ironic throwaway lines. Self-deprecating she might be, but she also made me laugh out loud. I'll be looking out for the next book in this series. No doubt.