To what degree should players be able to change the appearance of armor?

Personally I love being able to change appearance and color. Guild Wars 1 had an amazing dye system that allowed different color mixing once you found the dyes. As for shape I think aesthetics are just as important, always hated looking like Bozo the clown in 5 different colors and funny looking items. The ability to transmute your characters appearance creates more pride in the character.

As much as possible for me, but I still need to know who is a warrior and who is a mage, or no... would be extremely new and fun to don't know your enemy and be able to disguese yourself as a old man with mage abilities and when you go to battle you pick up a sword and a shield, "Oh crap, he is a warrior not a mage!".

And that warrior with his warrior gear could theoretically still be a mage as well. You could be a warrior with 4 weapon skills from the warrior set and 4 extra skills (non-weapon based) from any other class.

Jumping in way late to this thread. The first thing I notice is there is no option in the poll for players not being able to change the appearance of their armor, so it looks like that's bit been settled already.

Things I like from other games: DC UO let you pick a 'style' (some of which are cash shop IIRC). Whatever gear you wore conformed to that style, so you never had to worry about looking anything less than sexy when you put on a new piece of gear.

EQ 2 has the very simple but very effective 'appearance' slots. Any gear can go in the appearance slot - including special pieces that make it appear as though your aren't wearing gear: very nice for bare arms and no shoulderpads.

If you add some coloring options - dyes go all the way back to Baldur's Gate if not before - with the appearance tabs or style system, or some combination of both, you should be able to come up with a way to make your character look the way you want her to.

This is an important thing. The more you control you have over your character's appearance, the more 'connected' you will be to her, and that helps a lot with immersion into the game.