Carl Hiaasen writes fiction in exactly one vein: the South-Florida bunch-of-whackos black humor almost-but-not-quite surrealistic crime novel. Razor Girl is no exception. It has a cast consisting mainly of Hiaasen stock characters, a Key West setting . . . and not much else.
One thing it doesn't have is a Plot--the capital P indicating that there's nobody that has any kind of plan or goal or sustained intention that drives the book. As a result, it doesn't have much in the way of lower-case-p plot. A bunch of characters run into each other in various combinations. Some hilarity ensues. There is a crime, but it's kind of an accident.
Another thing it doesn't have is anyone who's particularly likable. The nominal protagonist is hardly better than the villains: self-centered, short-sighted, ego-driven, obsessional, a poor friend, and all in all a loser. The most sympathetic character is a mobster. In earlier Hiaasen, you could usually count on there being at least one person who a non-insane reader could identify with. You also got your share of nutjob-but-on-the-side-of-the-angels characters; those you could at least admire from a distance. In Razor Girl, it's jerks all the way down.
There are some funny bits. There are some clever bits. There are some bitingly sarcastic bits. The prose flows smoothly. The setting is well-rendered. That's what you get.
If you don't like Hiaasen, don't read this. If you've never read Hiaasen, don't start here. If you do like Hiaasen, you might use this one for an airplane ride; it will help pass a couple of hours. Don't expect much more.
If you're new to Hiaasen, I'd suggest starting with one of his earlier books: Tourist Season, Double Whammy, Skin Tight, Native Tongue, or Strip Tease.