I actually liked the game, apart from the really lame storyline towards the end. The city was created extremely well, if you've been there (Los Angeles), you'll probably recognize some landmarks there. The shooting part of the game is a lot better than GTA's, as is the driving and shooting (at the same time) parts. The cars themselves actually feel and handle very differently depending on which car you're driving. I liked the aspect of playing a cop (you can even frisk citizens walking down the street and collect drugs or weapons), but you also have these good cop/bad cop meters that raise or lower depending on your performance. If your bad cop meter gets high enough, the cops will actually start to chase you.
While you're driving around L.A., you'll start to get radio transmissions asking you to assist in stopping various crimes around the city (robberies, rapes, assaults, gang warfares, kidnappings, etc.) which are really cool for a while, then they start to get a little old. You don't have to help in these crimes, but it can be fun just tracking down someone and killing them (thus earning bad cop points) or arresting them.
Its a cool game, but it has its flaws, for the $20 it is now, its probably worth a try, if you're still skeptical go and rent it.
I didn't really have a problem with the S&M dungeon part of the game, I actually got through that part pretty easily. Have you checked
http://www.gamefaqs.com/ for a walkthrough of that particular level?