just tossing this up here for visibility, both for players and devs. i didn't know about this issue till recently myself. and then this post came along saying that unarmed great cleave for humans works as intended. it does not appear to do the same for elves, and to hear people talk about it i can only assume the same is true for many other races.
this is a short clip showing the elven unarmed great cleave and cleave animations, great cleave first, followed by cleave. using an unarmed great cleave in combat gives a pause that lasts for at least 1-2 full seconds before any damage happens at the very very end of the attack (to the point of being completely after the attack animation finishes)
it is also possible that this slower (incorrect?) animation for great cleave is not correctly attributing TWF and/or double-strike bonus. i did not do the most scientific test, as the only character i can test with is an acrobat, so focused on staves not much in the way of TWF, and not much double-strike to speak of yet either... but i beat down the dummy from full to dead using nothing but great cleave, and did not once proc more than a single hit