On the face of it, the purpose of Gotham City Sirens seems to draw a book full of hot women. Catwoman, Harley Quinn, and Poison Ivy band together: what's not to like? But I found this volume to have some pretty good stories in it. Not a lot of criminality actually happens, really. It's more like these characters get in trouble a lot, because of their history.
The stories mostly stood on their own okay, but the Poison Ivy story, the first story, made me feel a bit like I was missing some history.