As background, I have been, since February 2011, an avid Zeo user. When the company tanked I bought as many headbands as I could find and continued using the app on an old iPhone. So, I'm very used to wearing something on my head at night and very familiar with the information it provides.
It's taken me nearly a month to get used to wearing the SSB. It's not that it's uncomfortable, just very different. The binaural beats also, for me, took some getting used to. Generally, I don't think my sleep suffered too much during the acclimation. My sleep numbers on the Zeo prior to making the change were not that great, though they had been at one time.
On the other hand, I can't say my sleep has radically improved either judged from a subjective perspective. I don't know what sort of "algorithm" they just for the SSB and I'm sure it's probably very different from that used by the Zeo app, so I doubt the scores can really be compared. The jury is still out whether the binaural beats really help to lull me to sleep or get me back to sleep if I wake up. I have had occasions where I notice the beats fading out or coming on in reaponse, I assume to the feedback from the headband. So, that part works at least in that the tone comes and goes based on some criteria.
It's pretty expensive. The MSRP is $250 although I didn't pay that much for mine since I bought into the startup. So, right now, I would say I can't enthusiastically endorse it, but I wouldn't pan it either. I'm hoping they will make the app more sophisticated and provide more information on how the unit measures and calculates sleep quality. I'm expecting I will get more used to the unit and start sleeping without being aware of it. I believe the latter accounts for the acclimation period.
I'll continue to post my experience. At this point it's the only option out there to use brainwaves to measure sleep quality. That is what I really like about the Zeo and why I bought the SSB. Nothing else out there compares I believe.