The Honeywell Enviracaire HEPA Air Purifier 50250 is a large unit that can have a noticeable effect on large rooms. Some people may be put off by the large size, but smaller units are just not that effective. Since it circulates air very effectively, it can create a fan like effect, which may feel like a draft in colder areas. If you have allergies, this unit is very effective at eliminating air particulates that can cause irritation. Ease of Maintenance Cleaning or replacing the filter or pre-filter on this purifier is easy. Dust/Allergen Removal The air purifier has a HEPA filter, so it one of the best available. Filter Availability Filter replacements are readily available online, on sites such as Amazon.com, but may be harder to locate locally. Durability So far, so good, but we have only had the unit for about 2 months so far. It does run virtually all the time though, and has had no issues as of yet. Effectiveness When run continuously, the air is noticeably fresher and dust and particle free. Design Some people have complained about the indicator light bothering them, especially if it is in a bedroom at night. But turning the unit away or covering the light eliminates this problem. The unit is fairly loud on the high (more effective) setting, but it is white noise, so it does not interfere with sleep.