Does everything
Bixby can do pretty much everything. Start a playlist, turn on the camera, change channels on your TV. Bixby is for Samsung as Siri is for Apple, kind of.
A personal assistant that helps
Bixby is not only something you talk to or ask where the nearest taco stand is. Point your camera towards a landmark and Bixby will tell you everything you need to know.

Samsung are one of those companies that need no further explanation. A giant Korean enterprise that constantly break the boundaries of what is possible.
Our thoughts
A great application for Samsung Galaxy and something you probably should use a lot more if your phone or tablet is compatible. There is really no need to actually touch your phone if you can use Bixby effectively. If you do not have a Samsung device that is compatible, Bixby is not for you to use.