3 sourced reports, with what to check before you buy. Each one links to the page it was reported on.
Costly or dangerous
Made watery coffee then stopped working within a month (ECAM290.81)
The buyer states the machine started making watery coffee and stopped working within a month of purchase, and the repair was not completed after two months.
What to check. A formal consumer complaint records a brew-unit failure shortly after purchase; check warranty/service response time before relying on after-sales support.
Milk frothing stops after months despite cleaning (ECAM290.61.B)
Owner reports the machine stopped frothing milk after ~3 months; cleaning the system and disassembling the nozzle gave zero result, and a replacement carafe failed the same way within a month.
What to check. The milk carafe is repeatedly named as the weak point; expect frothing to degrade and plan for replacement or manual frothing.
Owner reports the grounds-container-full warning triggers with only three coffees' worth of grounds; the same review notes the machine runs out of water or beans mid-brew.
What to check. The grounds sensor can false-trigger; empty the tray when prompted rather than trusting the count.
These reports come from the pages linked under each item: owner forums, repair guides and workshops. They are not a diagnosis of any one unit, and a careful check of the one you are buying still applies.
Text from the Kriko Espresso & coffee machines catalog, version 0.1.1, under the CC-BY-SA-4.0 license.