I agree with you, it's cool but there's no way I could justify it. However, I think Lockitron offers more utility than this and, assuming I was allowed to install my own locks, I could see myself potentially using it
Hell, it'd be cheaper and probably less confusing to visitors for you to just yell from the couch.
Chui is also beneficial while you're away. If you're expecting to be occupied you can have Chui deliver messages for your. You don't require your visitor to have a certain kind of smartphone to work with your lock, and it can make your home more intelligent(ex: recognizing when you get back and automating certain tasks.)
Still requires having previously dropped the dough to get a smarklock. Given that Lokitron lets you remotely unlock/lock, it saves you the ~$200 this costs and only takes a simple SMS if the person doesn't have a smartphone
Hell, it'd be cheaper and probably less confusing to visitors for you to just yell from the couch.