Enough is enough. I'm about to release a YouTube video about the disastrous implementation of the Kasa KE100. It will be titled "TP-Link Kasa KE100 - AVOID purchasing!" There are a number of well-known issues that have not been resolved for years. In order of severity:

* Extremely poor hysteresis- TRV will fully close and allow a room to drop several degrees in cold weather before turning back on and overshooting. Massive thermal discomfort. Proper implementation is to keep TRV partially on to maintain stable temperature.

* Lack of features- Cannot see what position valve is in. Can't customise hysteresis or behaviour. Can't set temporary override to TRV when room is cold.

* Broken API- breaks home assistant automations. TRV shows as "heating" even when target temperature is not met and the valve is closed.

overall rating 3/10. The performance is significantly worse than an analogue TRV.

original thread describing the most important issue: https://community.tp-link.com/en/smart-home/forum/topic/715030