Undersea campaigns take a lot more prep because such products as Blood of the Sea not out when I start them. Overall I like the book.
I was hoping they would have included Age Chart and Height and Weight for the races not covered in Advanced Race Guide.
Also notice that the Locathah from Bestiary 2 has a 13 Int Score, I figure they would have a +2 Int Bonus, but Blood of the Sea states that Int is -2.
I been running a 'Pathfinder' Under the Sea campaign for the last 7 months. Naturally to have diversity of races for the campaign, I 'wrote' up some creatures such as Locathah and Cecaelia and while similar they not spot on with this product. (Also ran an undersea campaign in 2nd Edition over a decade ago).