I use them frequently, as my last few campaigns have centered around the Isle of Dread, which is like Jurassic Park with less fences and more rampaging demons, shape shifters, magical beasts, and Aboleths.
so far, the party has encountered an advanced Legendary Tyrranosaurus, a berserking ankylosaurus, a 60 foot long ancient crocodile, terror birds, velociraptors, a Quetzalcoatlus, a 60 foot long ancient snake, a Scorpion the size of a football stadium, a pack of allosauruses, an Albertasaurus/variant T-Rex, a diseased dimetrodon kept as a pet of troglodytes, a bunch of prehistoric giant, poison-barbed eels called Mashers, dire barracuda, plesiosaurs, steggosauruses, triceritopses, Brachiosaurauses, Elasmosauruses, and at least one megaraptor, as well as some half-green dragon raptors and such in a swamp where a dragon lives. so yeah. Dinosaurs kick ass.