I bought this after our trip to Vanuatu (oh, to go back...) so I could attempt to identify the fish I caught in my photos. It's a nice sized 'pocket' guide (you'd want a big pocket), perfect to travel with, and the color illustrations for each fish are gorgeous.
BUT, I have two complaints: It's hard to find the fish you're trying to identify if you've never attempted a fish identification before. Which, honestly, isn't the books fault - it's neatly organised into the different species, but if I've never seen a damselfish I have no idea that the fish I'm trying to identify IS a damselfish. This is made more frustrating by the fact that damselfish don't all have common traits, so two fish that could not look more different if they had arms and legs, could totally both be damselfish. I'm not sure this is a solvable problem, except with time and experience.
The color plates, while gorgeous, are not the same as photographs if you're a beginner trying to identify fish for the first time. I'd read that photos were better when I bought the book, but this title had the most comprehensive list of species and I figured it can't really be THAT hard. But it can, and it is.
I've still found the guide useful and I'm glad to have it as a reference in my on-going Name that Fish! project, but I have also ordered a different guide with photographs to use as a companion reference.