Got this to review 35 mm negatives that I'm scanning. It turns on and off without any hitches so far. The only thing I'm watching is the instructions said to hold the on/off button to adjust light level. I have not figured out how to raise/lower the light level, but, I mainly turn it on and off - have not really had a need to go to an intermittent light level. When I initially set it up, I tried to find intermittent light settings, but, never could. I chalk it up to me not knowing how to operate the unit.
There were multiple reviews regarding the usb port being weak. I have left the usb cable in and don't bother connecting/disconnecting it. Only had the unit for less than a month, no problems thus far.