Partial solar eclipse on October 3rd - how dark will it get?

Hi,
during the partial solar eclipse on October 3rd in Central Europe, about 50
% of the sun will be blocked out, as far as I found out for Germany.
Does anybody know, if these 50 % are enough to be perceivable at all for
someone who doesn't know an eclipse is happening? Will it only slightly get
darker, even on a cloudless day? Will you notice a change on a cloudy day?

Thanks for any help.

Christian