I had all the same problems with trying to attack someone...just couldn't do it!! I thought it'd be like <img src="/ubbthreads/images/graemlins/div.gif" alt="" /> but instead my character just ran around in circles, and this was the English UK demo.
I did try to click on the circle beneath the enemies to attack them but if this isn't what you're supposed to do, then why on earth are those circles THERE!??!
This is a nit-pick but the circles are also slightly askew to the angle of the ground in relation to the character models stances!