A stained concrete floor is usually cheaper than a concrete floor with tile or carpet. If the concrete or stain work does not work out for you then you still have the option of overlaying it with tile , wood, carpet, etc.
Concrete floors have easy maintence and wear well. There are a mind boggling amount of options if one desires. Saw cuts, saw cuts into patterns, sand blasting patterns, staining patterns, mixtures of stains and types of finish sealers. You might do well to spend some time looking at manufacture pictures advertising their products, home building or decorating pictures or such, etc etc.
There is a incredible amount of variables that can affect your final results be they good or bad.
As several have pointed out. References are good, actually seeing some past work is GREAT.
Personally I am a big fan of stained concrete.