I've used (and abused) this humidifier for a year now.  The humidity output has been consistent, and the lighted tank makes a great nightlight for my girls.  I have not stuck to the operator instructions as I have used it without a demineralizer and with tap (albeit spring) water.  Very pleased.  I'm about to order another one for my other child's room.

I only use this when we need it in the winter.  So my use is maybe a month or two a year.  It has lasted at least 2 years now. Works great to create water mist and is very quiet, however it has three things which I find detract from it.  Hence the 3 star review. 

1.  It has an extremely bright light which is difficult to mask easily.  I have LED flashlights that are dimmer than this thing.  No way that I know of to turn off the light.  I just drape clothes over it and run tape along the back. 

2.  The water tower is tall and the fill hole is small.  Because of this I can not fill it in a sink.  When I fill it in the bathtub the hole is so small that I almost always have water splashed over the tower.  When the cap is wet it is very difficult to remove barehanded.  The cap is textured, but not suffciently.

3. Cleaning this requires some small tools if you want to scrub all areas.  There small gaps that are hard to reach, even with a toothbrush. 

We have had this model only a year and just brought it out for the next season and it stated off working ok.  However, soon after the fan motor started making noise and often locks up.  We have used it just as it says to even using filtered water.  Not to happy to pay $40 some buck for something to have it only last a few months.