Product review (5 stars): BEST in market. Had mine for 5 years. Best Beauty Secret too!
First off, humidifiers are the secret to beautiful youthful skin. And no flues or colds. Happier kids and babies too.
I run mine 24/7 even in the summer. Because I don't want dry air though I'm using the air conditioner. Dry air is bad for you.

Pro's.
If you want gorgeous skin, great nails, have a humidifier running 24/7.
Keeps household healthier: less flu, colds and allergens because air is cleaner without adding dust to air. It collects dust.
If you want healthy organs, they need moisture too. It's already been proven that people with humidifiers do better in the winter with less sickness. We never get sick.
When you run a humidifier the home feels warmer. Your humidity should be around 30-35% at all times in the house. Not so much that you have water on the windows. Not so little that your throat, hair skin feel dry.
I could not live without this humidifier. I have tried so many. They don't have enough output for large spaces, and they don't clean the air. That is huge for us because we pets.

Maintenance:
Its up to you to take care of it. That means you clean it weekly and then major once a month.
We don't use the cleaners. My husband cleans it once a week with clr and sometimes plain vinegar and water. He also takes a toothbrush and cleans the wheels of algae, build up.
We also don't use the additive in the water. That defeats the purpose of being healthy. If you let the water sit without running, sure you will get bacteria and algae but we change it daily. You have to.

Cons:
Okay the clicking noise does exist -it comes and goes. But for us it was only after we had it for a few years. This machine is funny. Its haunted. Sometimes it works perfectly with zero noise and other days, its clicking and then since ours is so old, it stops working. When it started to drive me nuts after 5 years and we thought we needed a new one, my husband broke the whole unit down and cleaned everything-fans and all. Kind of did major maintenance on it. So if you can't do this yourself you gotta take it and get it maintained.  We will probably need a new one sometime this year. This time I'm going to buy two. One smaller one for the living room and kitchen and the same size one for the master bedroom.

They are still the best humidifiers on the market despite their issues. You simply have to be a bit handy and put effort in to maintain this machine. If you are a low maintenance person, than use all the venta products to wash the unit and follow them to a t. But you will still have to clean the dust that gets on the fans and keep that area clean.