Actually, the bulb provides a very bright and good (natural) light. Unfortunately, however, the bulb every 10 to 40 minutes a misfire from about 1 second ... :-( Heat buildup I would rule out, as the bulb stuck with us in an open-topped uplight and the bulb after 10min was not worth mention hot. When I read the other reviews, it looks more likely after a production error of Philips from ...