I have one myself. I haven't been running it for long. But seems that it can do ~1.5TH/s without overheating even at ~28°C ambient. I haven't measured wallet outlet power yet. But it claims to be doing about 50J/TH.

Of course, it costs enough up-front that you're very unlikely to make a net return over the lifetime of the device even with free power... But they're fun and very easy to setup.