For one, on our model, there's zero peripheral vision. This makes it really hard to orient yourself in space - how far away is that wall? Did I scoot far enough past that doorway to swivel 90° to the right and go through it? Am I about to hit someone?
The same problem occurs when you're trying to talk to people. You can really only see two people who are standing in front of you. I'm not even sure if there's stereo sound - as there appears to be on the Snowbot, since he swivels towards people who are addressing him.
Other minor difficulties:
* it was difficult to park it into its charging station, which meant that sometimes it would just go comatose in a hallway.
* there's still a fair amount of lag, which makes it slightly annoying to have a conversation. Dialing someone over Skype/Hipchat/whatever-video is almost always the better option.
* sometimes you'd remote in, and be in an unfamiliar location because the robot wasn't returned to its parking spot. Since the whole point is to be able to access remote locations, we typically weren't familiar with the office layout, and would have to wander around aimlessly trying to get someone to help us get to where we needed to go.