I bought this around Christmas and it was the best investment! I have animals and a nephew that comes over often with major allergies. Since we've had this running, his allergies are way better when coming to the house, which is fabulous! My house doesn't hold the "dog smell" anymore either, which is fabulous as I love my dogs, just not the smell. I would highly recommend this product to anyone!!
The unit is extremely quiet which is great for using at night. It's also very simple to see if the air around you is not clean because of the different colors the unit shows. After using it for about a month, it seems to really help with allergies.
I bought this about 2 months ago. Haven't had a o change the filter at all. It's quiet and it's smart. When it senses the air is dirty or senses more impurities, it turns up higher, as long as you have it in auto mode. I like it. It's about the size of a thing of Hawaiian punch! The big bottle!