People on here think he's a demigod, and most of the world shouldn't have a reason to give a damn because he isn't all that important.
I have a Nest and the only thing I wish it wouldn't do is turn off the air at all when the weather system knows that it's very hot outside (perhaps this has to do with poor insulation, though). Otherwise, if you turn off auto-away during heat waves, it's great. The home I live in has pets and the thermostat is located on the top floor (it's old and the layout is less than efficient) so having access to it from anywhere in the world in an easy-to-use manner is incredibly useful.
I think Nest is far beyond the beginning. They have a shipping product in use with 1000+ reviews on Amazon. Investors aren't going to care if one investor had a problem with the unit.
More importantly you probably shouldn't care or worry about investor/user who reacts on a single tweet without knowing much context.
The tweet says nothing about what was the problem, or details about why he might have any particular problem while others didn't, it could be the way his office is designed.
He just expressed his opinion in as few words as he could, it could be for legitimate reasons or it could something silly he overlooked.
All he did was say it didn't work for him. Maybe his case wasn't handled well by the company, but it doesn't mean that just because he said that he's burying a company that's (as far as I know) been proven to sell a good product.
Like seriously altered the course of a startup's success? What's his most epic one?