I had a failure on my Anova WiFi after only ~4 weeks of use, the temp stuck at 0°C so it seems the temperature sensor had stopped working or the controller was not getting the input from it. Doing a search to see if this had happened to anyone else I came across others, it seems likely that steam getting in the vent could be a problem. I've never had the temperature above 66°C, but there was still steam rising from the water bath.
I contacted support and provided details and pretty quickly a replacement unit was on its way. A failure in an expensive product is disappointing and without good support I would warn others off this brand, but the quality of support makes all the difference.
I've bought a new container with a silicone lid that has a cut-out for the Anova precision cooker, I'm hoping to stop steam from getting anywhere near the vent on my replacement Anova. I'd happily recommend the Anova because it is a really nice unit that works well and has great support! I'd also recommend blocking the steam (especially on longer cooks) from rising up near the vent. Before my unit had a problem I had read nothing about potential problems from steam, Anova should probably have a prominent warning in the manual, or even better they should revise the design and eliminate the open vent.