The first thing to note is that this manufacturer sells the identical product under two names, SleepMate and SoundScreen. The only difference is the name--having "SleepMate" on the label was deemed a bit awkward for office use. They're both exactly the same otherwise.
I bought this based on wildly favorable reviews online. I found no one who rated it anything less than "incredible." I am extremely sensitive to noise. If a bit of the neighbor's stereo noise bleeds into my home, I'm completely unable to tune it out. I can't read, and sometimes can't even watch TV comfortably. Unfortunately, I live in an area of dense apartments--where the weather is such that the windows have to stay open--and my husband snores. I sleep with earplugs, but the noise can still keep me awake.
In the past I have tried other noise machines that didn't work for me--things like "rainfall" cds or electronic noise machines with similar nature sounds. The problem was that they play a loop of sound, and you can hear a pattern as the loop replays. Once there's a pattern, there's something to pay attention to, and your mind does not tune it out well. This machine generates pure "white noise," which I hoped would be more helpful.
The product is the size and shape of a fat smoke detector. Two things surprised me when I first received it. First, it was quieter than I thought it would be--even the loudest setting seems quieter than a window air conditioner. Even still, my husband complained he wouldn't be able to sleep with "all that noise." (He got used to it within a day or two). It sounds something like a fan--a rush of air. Although you can adjust the volume and tone somewhat, the highest volume is also the highest pitch. Personally I wish it had a deeper tone.
The second surprise is the instructions say to place it *away* from you, so the sound can "fill the room." The ideal positioning pictured has it on a high dresser across from the foot of the bed. Unfortunately, my only option was to place it on the bedside table. I don't know if this really affected my results.
After using it for a while, I would say that it makes it a bit easier to tune out noises, but by no means covers them up. So, once I'm asleep (I still use earplugs), I can stay asleep. If I can manage to get my attention focused on a book the neighborhood noises probably won't break my concentration. But once I hear the noise I still can't tune it out. In fact, a couple times I have actually turned off the machine so that I could identify some sound--not knowing "what is that?" was actually bugging me more than when I could hear it clearly. But like I said, I'm a freak about noise.
This would be ideal for covering traffic sounds--it's just the right sort of noise and pitch. But if your problem is a neighbor's stereo, that mind-numbing bass is not going to sound much different with this than without. It really doesn't "cover up" sounds, but if you have a reasonable ability to tune things out (unlike myself) and just need a little help, you will probably be very happy with this. And it's definitely helpful for *staying* asleep, even for me.
It doesn't solve all my problems, but based on the reasonable price I'm satisfied with the value I got for my money.