I haven't had the purifier long enough to talk about reliability, but about a 1/2 hour after I plugged it in and turned it on I was breathing through both sides of my nose.  It's been years since I've slept without craning my neck to breathe, so this has really changed my life for the better.  Easy to get up and running and it works just as I'd hoped.  I run it on low all day and on medium at night.  I have a smoker in the next bedroom, a dog and a cat, and I'm not bothered by any of it.  If you're stuffy all the time, like me, I highly recommend you give this a try.