I own one Nest Protect, two Nest thermostats and an indoor Nest camera. All of my products have exceeded expectations, brought great return on investment, and have amazing user interfaces.
Just last week Nest sent me a newer version of a smoke detector I had purchased from them about 5 years ago, just because they no longer carried the inexpensive wall mount piece that I needed to replace. I didnt even ask them to this and I went into it expecting to pay for my lost part. They sent out the replacement to me the next day at no cost. Thats a company that is interested in customer loyalty.