I've been using VR Commander every day for two weeks now, and here's my experience with the program.

VR Commander is simple to setup, and easy to start using.
The user guides are useful, and the options are clearly explained.
The user interface is clunky, but it does try to remedy this via multiple paths to often used commands.

There's no training required, due to its nature as a command pattern matching engine.
But also because of this, there are nominal false positives (roughly about 5% from my own usage).
I further reduced false positives by picking phonetically distinct words for commands I don't want to have mistakes in.

There are some glaring problems, however, as VR Commander seems to randomly stop listening after a while.
At times, it seems that the program has crashed, and must be closed and restarted to start accepting commands.
Other times, it seems that the program has gone to sleep or stopped listening due to false positives on its built-in commands.
Even turning on confirmations doesn't seem to help. The the false-positives manage to worm their way through and shut down the engine.