Product review (5 stars): Fantastic! Keeps humidity in 35-40% range. You will need multiple units.
I purchased total of four of these, in two separate transactions, to replace my standard humidifier. Best purchase this winter. Not only that they replaced the humidifier, they work so much better. Between four of them humidity has stayed in 35-40% range this whole winter. I was never able to get that with standard humidifiers (several different ones) in the years past. On days when heat is running more frequently, expect to fill them up twice in a day. Some see this as a downside, but to me it makes sense  they are adding moisture to the air, so they will use water. Also, make sure to get enough of them for the size of the room/rooms you are trying to cover. Four I use work well in about 800ft^2.