I have a Shark steam mop for the kitchen tile floor. It does work well, but I typically use it more as an in between deep cleaning tool. It works well enough for regular cleaning, but every now and then, I think the floor still needs a good cleaning with a mop and floor cleaning solution.
If you plan to get one, I would recommend not cheaping out on it. Get a good quality one, or it just won't get the floor clean. I know plenty of people who tried cheaper steam mops and hated them because the cheap ones just don't do a very good job.