How beardedness affects women's attraction to men
New research suggests that women tend to find beardedness attractive when judging long-term relationships, perhaps as a signal of formidability among males and the potential to provide direct benefits, such as enhanced fertility and survival, to females. Ref. Source 2x.
As a bearded man, I can say I get many compliments on it, from both men and women. My wife especially tells me all the time how much she likes me to keep a trim beard. If it gets too long or unruly, she doesn't like it, but having a full beard that is well kept is her ideal.
From my experience among my friends, it seems that either a 5 o'clock shadow or slightly more is the best way to attract female attention. In high school we all had to shave every day, and if you had so much as a little stubble, they made you go shave it. So most of us grew something as we went off to college, and I would say it was definitely a hit.
I must be the odd one out among women because I don't really care for it, I prefer to see a clean shaven face. Mustaches aren't trendy anymore but I would rather see that than a full beard even if trimmed.