I'd say Vessel is more of a 3.5, but I'm upgrading it to a 4 star rating out of my sheer amazement by everything Durst.
Vessel was interesting. I liked the premise and I found the world to be intricate and fascinating. I liked the morality of it, how ethical concerns were central to the story rather then just survival. I loved most of the characters. They were real people, with good sides and bad sides and in-between sides. I loved how desperation was shown in the tribes and how they were dealing with a horrible drought. People were suffering and it brought out the best and worst in them. It was such an uncanny representation of real life that I got goosebumps.
That being said, this book had some real problems. Durst really seemed to struggle with the traditional fantasy concept. Part of it is the logistics of creating a whole new world for one novel. On top of that the actual plot of the novel moved very slowly. Her world building really slowed the book down and the events never felt very crucial. Unlike other books of her I was able to put it down, even right at the very end. The romance was....off. I can't describe it without spoilers but I can say that it ended in a remarkably unsatisfying- if logical- way. That was just part of the larger disaster that was the ending. Nothing was really resolved so much as stopped abruptly and assumed it would all work out.
So yeah. If you're a Durst newbie I would suggest starting with someone else. If your a diehard fan just go in with realistic expectations.