Not as easy as it should be.
Crutchfield Customer Review (What's this?)
I used the old X10 tech for some time. It was subject to spurious signals and had trouble across phases in a multi-phase power system. The z-wave tech seems to work pretty reliably. Besides the hub, I have some lamp and switch modules and a scene capable switch. In order to get the scene capable switch working, I had to locate a device handler which I found in the SmartThings forum posted by another user who had coded it. Then copy paste that in to the SmartThings Groovy IDE with several more steps to final get it working. A bit too difficult and complicated for many. I plan to add some wall switches and a door lock in the near future so we'll see how that goes. There were also two apps, the newer lacks any widgets (android) and has no routines found in the classic app. The Classic app widgets didn't show any status information and were basically shortcuts to the Routines automation. Using secondary controllers has been un-necessarily difficult as well. I feel like I'll need to learn to code with Groovy to get the most out of the SmartThings hub.
Pros: Better than the older X10 tech. Numerous z-wave devices available. If you don't like how things work, you can learn and code it yourself (or possibly find someone who has already).
Cons: Two apps. The newer app is missing any widgets. Copy/pasting (or writing your own) code often necessary to get devices working is too difficult. Secondary controllers are difficult to add.