I prefer technology that hides from view, so the Withings watches suit me as well.
The biggest downside is that the battery does not seem to be user-replaceable, so the 1 month of run-time I used to get slowly fades down to about a week or two after a couple of years of use. I can't go away for more than a week now without bringing the charger.
I agree (a ScanWatch 2 owner here) that batteries should be user-replaceable. And that the fact that it is missing from my watch is a negative thing.
However, it is a very minor thing when the battery lasts as long as it does. If it holds 80% capacity like most other batteries today at 300, or more, cycles it would take over 10 years for the battery to degrade significantly considering each cycle is up to 30 days.
The biggest downside is that the battery does not seem to be user-replaceable, so the 1 month of run-time I used to get slowly fades down to about a week or two after a couple of years of use. I can't go away for more than a week now without bringing the charger.