NOTE : In cRPG, you can either use attack and block directions controlled by "mouse movement" or by "inverted mouse movement". By "mouse movement" means your mouse movement will correlate to the direction of your PREPARED ATTACK, and by "inverted mouse movement" means your mouse movement will correlate to the actual RELEASED ATTACK.
It may seem initially that because of this, inverted makes more sense - however because of more advanced mechanics like parrying, feinting, and chambering, most skilled cRPG players would suggest learning in MOUSE MOVEMENT mode if you are not familiar with either.
This is a topic of great debate, but I personally think inverted mouse is easier and more effective. The reason is because it makes turning into swings much easier; the swing and the subsequent turn occur with one fluid mouse movement. With non-inverted, you have to switch mouse movement direction during the attack to turn into it, and you have to time this perfectly or your attack will land late. I used to use non-inverted, and I was constantly getting out-swung because I didn't turn into my swings as effectively. It also gives your opponent an early clue about the upcoming attack; if someone is turning right and pauses for a split second, it warns that a left swing is coming.
I can see where non-inverted would be better for chamberblocking, since it better enables "turning into the block", but no one I know relies on chamberblocking in actual battle (maybe 20 people are even good enough to rely on it in duel). However, turning into the swing is pretty much a requirement in battle/siege (since everyone does it), and non-inverted makes it more difficult.
Semi-related question: is it possible to bind attack direction to mouse button? I.e. left swing mouse button 3, right swing mouse button 4, etc. That would be the ideal, as it decouples turn direction from attack direction, enabling less predictable movement.