User blog comment:Care Level/Fucking Sightstone, Man./@comment-24509120-20140421195902/@comment-9593635-20140421213017

Somewhat, but these wards are more postured to give an advantage in fights, e.g. they should be placed around objectives moreso than just "around the map"; there are other wards for generic vision. Also, the cooldown is short enough that you could drop Standards for vision and still ward up for objectives.

Even if Overwatch does give away the ward location (the slow), the enemy team still has to either pink or sweep to clear it. And, even if they choose to avoid it altogether, its presence is still having a huge impact by forcing teams to take less-than-optimal paths in order to remain hidden.