30ish male here, formerly bearded, shaved, now have a short goatee/van dyke
I believe beards depends on the style of facial hair, face shape, fashion style/clothes, and other factors such as age.
I'm straight, but I have no qualms about noting whether a man has good style choices or not.
I'm don't look stylish myself, not enough money-time-indecision on what suits me, but I feel I have a handle on what works with others.
Style of facial hair, unless you're in a daeth metal band, don't do the long braided goatee.
Let's come to terms with styles: http://www.ftmguide.org/facialhair.html
Style is intertwined with the other factors, but beard style can also say a lot about your personal culture. It's tenuous, but here's what I see when when I encounter a new beardy
Long goatee only = hardcore
pencil or pencil plus soul patch = urban
chinstrap = art or film school type
full Garibaldi beard = religious associations, old-school jewish, orthodox, islamic
Shenandoah (Abe beard)/Amish/Old Dutch, etc = Amish
Chevron = Cop, National Guard, Government employee - They are often not allowed to grow beards, but can grow neat conservative moustaches.
handlebar, or horseshoe = biker
Circle Beard (goatee connected to moustache) = common, baseball/football/nascar fan, has baseball cards and maybe an old camaro.
My fav combos include moderate length full beard if the person is youngish, long straighter gandalf beard if the gent is older than 55 or so. I also like the Van Dyke and Bablbo - more hollywood-stylish and escapes the stereotypes from above. Also flattering to the chin. Another nice variant is the long Circle or VanDyke with a shorter chinstrap: the Obi Wan beard from episodes 3-6.
Face Shape - hmmm. Beards can help here or they can hinder. A weak chin can be hid with a goatee (chin only hair) or with a Van Dyke (goatee + separated moustache). If you do the VD, keep the moustache part shorter and grow the goatee part longer.
Short hair - most styles as long as the hair is not spiked. Otherwise, the templar look is great - King Leonidis (Butler) in "300", David Thewlis and Liam Neeson in "Kingdom of Heaven".
Mid length hair is tricky. If it's well layered or tossled or just natural grow out, most facial hair looks good. Think Russell Crowe in any scruffy stage, Old West guys, etc... Christian bale in his wandering stage in Batman, but he looks good in whatever. Blunt cut, Poofy on top, modified bowls or emo asymmetry cuts don't work well with beards.
Very Long hair can wear most facial hair types. I guess the long draping hair well balances out anything that could go wrong with the facial hair. Might could be said about being completely bald too.
Fashion is self explanatory given the above.