Nest hasn't been that impressive to me, but they're better than a lot of other home automation/security providers, including the one who completely mishandled a security disclosure I made a couple of months ago. The issue was remedied, but it was very unprofessional, and I didn't bother doing digging deep. I am certain there are many other simple security issues with that platform, just waiting for someone to decide that they want to play a game with $IMPORTANT_PERSON_X's home locks.

It's definitely wise to think twice before making your home's basic functionality, like allowing the owner to unlock doors, depend on systems that require an internet connection.