The placebo effect is a very real thing. Any time a company can market a product as being extremely believable then chances are, there will be a good percentage of buyers that wholeheartedly believe in that product and its results too - even if it's no better than what's already on the market.
No, I do not believe the new product "Sense" will be that successful in helping people get a better night's sleep. In today's world, people have to deal with a great deal of stress in their lives. It is a proven fact that stress is a factor that affects our ability to fall asleep and stay asleep. I believe we need to relieve the stress in our lives in order to sleep better. This product cannot do that.
I think that the device may be quite capable of telling you what is disrupting your sleep, but most people already know why they are having trouble sleeping - They just can't seem to do anything about it. Overall, I think it will be a big waste of money for a nifty gadget that doesn't do much in the end.
I think this is way too complicated to be solved by an app on your phone. I think how stressful your day is plays more into your sleep than how hot your bedroom is. I also don't understand how it would work if you share your bedroom with another person. I think it sounds interesting but won't accomplish much.