I live with the founders so I've had Lockitron for about a year. in my unbiased opinion: it's absolutely amazing especially if you have a lot of house guests (hacker sleepovers).
I'd be interested to hear what kind of backups the founders have. My biggest worry would be what do I do if something happens to my phone while I'm out: broken, mugged, or even just the battery died. It would suck if on top of that I couldn't get into my own house. Do you guys still take your keys with you, or keep a spare around?