Turok: Dinosaur Hunter is a fantastic shooter. It's not particularly deep, but it's a solid entertaining time, and you can really see how the FPS genre was inspired by this game. This PC port is comparable to the N64 version, but with cleaner graphics, and a bit smoother. The array of weapons is good, the soundtrack fast-paced and well-suited, the enemies are designed well, including the bosses.
As for some negatives, some of the levels can get a little to labyrinthine for their own good (which can also make it hard to find the keys as well as hinder navigation), and a couple are probably a bit too similar, with there being a heavier theme on natural and tribal settings than more overtly fantastical sci-fi, but nothing too. I kinda wish there was more focus on the story, as the backstory and universe is really interesting, but it's fine without that. Finally, the sound effect when you collect health and triangles can get annoying real fast.
To finish, I highly recommend this game! If you're a fan of shooters, this'll keep you entertained for days, and I can guarantee you'll probably only yell at your computer a little. ;) Also, $20 dollars is hardly a steep price. I think it's a perfectly reasonably one.