I've been running one of these for a couple of years now. It has been in pretty much continuous operation since I got it (night and day). The noise factor is tolerable for a bedroom. I even kind of like the "white noise" factor for sleeping. I keep it on the medium or low setting. I feel that I've gotten a decent, but not outstanding, value for my money. The unit is still in operation and I expect it to last several more years. As far as effectiveness goes, well, I have 2 cats and no longer get the sniffles when they sleep on my bed.
There are a couple of things that annoy me though.
The first is that Neoair has failed to penetrate retail stores, so if you want another filter you have limited suppliers - most of which are online. With other purifiers you can go to Wal*Mart and get a replacement filter. I dink Neoair half a star for lack of convenience.
The second irritation is what I feel to be a flaw in the design of the filter itself. The HEPA filter Neoair supplies does not have a rubber gasket around it. The unit itself also does not have a rubber gasket in the area where the HEPA filter goes in. Since there is no gasket, air rushes around the edges of the filter instead of going through it. You can see dust collected on the secondary filter behind the HEPA filter after a while. What this tells me is that the air purifier is sucking air in and spitting it back out without filtering *all* of it. Other air purifiers I have seen do not have this issue (or the problem is lessened) because they use a rubber gasket around their filters. In my Neoair, for example, there's enough room for a 8.5x11 sheet of paper folded multiple times to fit in the gap between the filter and the filter housing. That is actually what I use to keep air from rushing around the HEPA filter. For that design flaw, I dink them another 1.5 stars. This seems like an issue that could be fixed with a minor modification to their filter manufacture, but I haven't seen that happen as of early 2008 (when I last got my filter).