Like another reviewer, I quickly got annoyed with the bright blue lights and the loud beeps from the controls, but it really is simplicity to remove the base with a screwdriver and disable them with a snip of a couple of wires. To the user who found it got wet, it is vital to ensure the 'steam' nozzle is well seated in the lid, or it can have a tendency to dribble.
Having experienced other ultrasonic diffusers (my parents have tried a couple of different models) I was really quite impressed with this model. The large water reservoir means it runs happily for a good few hours, even on continuous 'high' mode (rather than the timer modes also available). The automatic cut-off works well to protect he ultrasonic 'element' from drying out.
Rather than using this for aromatherapy, I use this with Olbas, Karvol or Eucalyptus oils when I have a cold. As I sleep on my side, I find I get badly bunged up. I used to use a candle-based system home-fashioned out of a couple of interlocking food cans and, while it worked well, I was never comfortable leaving it lit while I slept. The quiet, cold operation of this unit leaves me with no such qualms.
It is important to ensure the unit is completely dry when storing, especially if you live in a hard water area. I ended up with chalk deposits, but they were quickly removed with a little vinegar.