Generally, not good. Hard surfaces are reflective. Even rooms with carpet usually need a good number of absorbtive treatments on the walls to acheive good room acoustics. You can compensate by using a throw rug over the tile if that is your only choice.
Hard surfaces like tile or wood are fine and even preferred by many, including myself. Like Brian said, you are definitely going to need sound absorbers on the wall and especially the ceiling. I say especially because the ceiling is often overlooked. But it is far more important to treat the ceiling than the floor. The floor is reference, always the same distance away. We are used to hearing reflections off the floor everywhere we go.