I used to use the BGE until I found that unity can build to lots of different platforms. What platforms does the BGE support?
Windows, linux and mac. Although google may have helped a little, I think you might find more answers here: http://blenderartists.org/forum/forumdisplay.php?34-Game-Engine
I think it is better to use Blender to make the assets and Unity as a game engine. I only use Blender as a hobby for modelling and scripting but I think Unity will provide a better base for game development. It helps that there is a free indie version and this year they created a steam like store where you could sell a game making distribution that much easier. Sometimes the blender game engine does not play so nicely with some graphics cards, you might find evidence of this frustration in the forums.