Update 26/03/2015
In the 3rd trial I've actually get a working collar ;-)
So far I am therefore extremely pleased. The brightness is more than adequate and so far our very active dog has not yet managed to go unintentionally to open the shutter. The battery lasts too loose for several long walkies rounds - not much to complain about from there. Even in wet weather there was so far no problems.
In my opinion is negative, that the battery is not easily reversible. So already resonates with a bit of bland aftertaste of a relatively expensive disposable article. This would have been technically definitely different solvable.
The collar will turn on as soon as the touch shutter contacts. A switch to turn it permanently, there is not.
Since the collar, as written above, has not yet been solved inadvertently with us, I see the point neutral. Should this happen to anyone but are, if you're unlucky and no longer finds the necklace in the dark, about 40 Euro times just gone.
Based on the last two points I give "only" 4 stars.