We use Lockitron at the 500startups offices. It worked well most of the time. The few times it didn't work was very annoying and I had to rely on someone else to open the door for me (from the inside). As long as you have a secondary option for opening the door, it's a great product.
We use it at Getaround and it works well all the time. We once had our internet line go out and couldn't lock our office until we found the spare key, though.
