I finished it a few weeks ago. I thought that it was OK. The two best things about it are how it captures the feeling of the movie and being RoboCop and how satisfying and violent the gunplay is. It reminded me of the old first-person arcade shooters because you have limited mobility and the amount of damage that you take is largely determined by how quickly you can take down the targets. I like to stay relatively still in single player shooters while I aim, so this gameplay suited me well. If you enjoy shooting ranges, all of the combat is like that. You can shoot body parts off, which is fun and would make Paul Verhoeven proud.
The two worst things about the game are probably the world/level design and side missions. You spend half of the game in only two maps: the relatively small police station and a relatively small neighborhood that you visit over and over. The latter allows you to explore a bit, but there's not much to do outside of a few objectives. The rest of the maps are very linear. The side missions are some of the worst that I've seen in a game. For example, one is to fetch a towel from a locker room, another is to find and rescue a cat and a bunch more are to give out parking tickets. Being a towel boy, feline savior and meter maid all felt beneath RoboCop and like padding to make the game last longer (but even doing them all, the game takes less than 10 hours to beat).
So, there's some good, some bad. It's not a great "game," IMO, but is worth playing, anyways, if you're a fan of RoboCop.