This hat is sized "large," but still didn't fit right on my head.  I let a friend try it on, and it immediately fell down to her eyes.  But the extra space is more in the width than the length, so if you have a long head, as I do, it still may not fit you.  The hat has a hard shape without give, so fit is particularly important.  Being a tall hat, it will also fall down too low if it's too big (I inadvertently discovered a fix for this--costume cat ears).

The hat survived a long evening of being roughly crammed onto my head only a little worse for the wear.  The inner structure of the brim broke in a couple places, but it wasn't noticeable.

This hat looks ok.  I wouldn't wear it to an actual nice, formal event, but it looks good enough for most costumes.