There were reports of the "Attempt permroot" function in the app failing, especially after applying the G2 OTA or if their phone came with it pre-installed (and it's uncertain whether or not the app was updated to properly support the OTA). After it failed, the phone would be in an unknown state (sometimes stuck on the HTC screen, sometimes in a bootloop, sometimes unable to temproot anymore, etc.). A lot of the time, once the phone was in this state, other methods of rooting wouldn't work as is. What made the problem worse was that if you had the OTA installed, you couldn't use the shipping ROM to restore completely back to stock and start over without at least having temproot to downgrade your version number.
That's why people tend to not trust Visionary anymore. Once reports came out of it being hit or miss, it became more prudent to recommend the other methods that were at least more easily recoverable from if something messed up. That being said, I don't think there is a problem with it if you are only using the temproot function. I just wouldn't recommend anyone hitting the permroot button anymore when safer methods exist.