Sigh. This is the problem with reviewing books way after you read them: you can't remember what your exact thoughts were. Anyway, here goes nothing.... 
 4 stars for Lord of the Abyss 
 Nalini Singh has this writing style that just appeals to me. When I pick up book she has written, I know, more often than not, that I will enjoy her work. Lord of the Abyss is no exception. I liked the writing and I like the characters. Micah made me smile a lot, and Liliana was a brave girl. Both hero and heroine deserved each other - in a good way: they complemented the other. the story development was the best in the quartet. With regards to sensuality, the heat factor was rather amped up in this one, so that it was more like Gena Showalter's than Jessica Andersen's or Jill Moroe's. All in all, I do think this was the best in the series as a whole. 
 Why I gave it three stars 
 The series as a whole is not very well done. As a quartet, I felt it was not very cohesive - there were no ties that bind. A few senteces about siblings here and there didn't connect the works quite as well as I'd hoped, so that was disappointing.