Benefits:
Spring: keeps you nice and warm in the crisp mornings
Summer: er
Autumn: keeps you nice and warm
Winter: better than a scarf anyday!

Disadvantages:
Spring: windy |-|
Summer: oh my god. So hot. Sticky hair not nice.
Autumn: windy is baaaad.
Winter: nope can't think of any

General Pros and Cons:
Pro: looks nice
Con: uses a hellofa lot of shampoo and don't even talk to me about conditioner!
Pro: Can style it in many many ways
Con: can make me look roughly 12 years old
Pro: Goes with anything
Con: Takes time to faff about with
Pro: men more likely to drool over long hair
Con: Gets in the way. A lot.
Pro: good galsses cushion for ears
Con: Leaning over candles/smokers is an extreme sport, as is hairspray near candles/smokers
Pro: feels niiiiiiiiice
Con: Tickley
Pro: if ever in need of material to make a rope with...
Con: If you thought cats and dogs leave hair everywhere you should try long hair, kicking animals asses
Pro: generally looks just as good when wet
Con: After bath time you find yourself with hair in crevasses
Pro: Short hair would make me look even younger and boyish 8|
Con: when down is hard to get the sweet innocent look that really suits me