Dalek security guards

Micro-soft-in-the-head are trying out robot Dalek like security guards. The robots are armed with camera, sensors, sirens and microphones, but no weapons... yet.
They never sleep, say the company Knightscope, well only for about 20 minutes every 24 hours while they recharge.
Now this may seem like a good idea, especially when you cost it at about half the hourly rate of a human security guard.  There are some points to be aware of though.  first the robot can't actually detain anybody, only summon help, secondly it could be fairly easily tipped over, it is heavy but I suspect someone jumping at the top would tip it over, and it can't self-right, but by far the biggest issues is one the early Daleks suffered from, it can't climb kerbs or stairs.
Of course serious criminals also might have no fear of shooting or ramming a robot, but they just might hold back from a murder charge, and a real security guard can dive for cover and return fire.
Also bare in mind if works from wi-fi, so the hackers will have a ton of fun.
Come on guys, you can't solve everything with technology, most of the clever stuff never works properly anyway, how long before your Dalek gets a virus and starts knocking old ladies over for the fun of it!