1. It doesn’t have an adjustable thermostat, so I can no longer make tea directly from the tap.
2. It tinkles.
After perusing* the manual, I found out that what this one does is fill completely with water (sensor at the top, no doubt) and as it heats up, the water expands (basic physics) and so it has to have an overflow valve (set to 7 bar**, this is the only thing labeled on it). Every time the pressure builds to that point, I hear a little tinkle in the kitchen. Just a short little tinkle every five minutes, until the water is back up to temp.
Oh, to give a merry little tinkle every time I felt pressure.
* I love that word, used it all the time back when I did theatre.
** which, from my bicycle manual translation days, I know is about 100 PSI (OK, 101.5 something. I was editing for accuracy, after all).