Me n my friend have been playin this since last week thursday or friday.. i forget. but yeah, I have to say, although im no soul calibur lover, i do like it alot, especially SCIII and so it did take me a long time to get use to SC4.
As stated before, theres quite afew changes. one of my biggest complaints was the inclusion of ~new~ characters. i mean, Darf and Yoda arnt really new, theyve been around longer than I have, the apprentice is pretty amazingly flashy and cool, but i cant use him for crap. amy was in III and the 'bonus' characters just use other peoples movesets (for example, the robo girlie is astroth). so really, its just hilde and the boss dude (who is pretty much a game end kind of guy ) but then again, there are some main characters who have changed sooo much, that they are like new characters anyway. my main dude in III, yung, is almost totally different. gone is his slide back stances and moves, and nearly every other move to be honest. its like, they have stripped everyone of what they feel were unnessiccary, but thats left them with like 3 moves each ¬_¬ but, once you get used to it, you realise that this isnt soul calibur III. yung is infact (as i like to class him) a speed and crush type. hes quick (well.. quick for SC4 anyways) but his moves (espesh his forward triangle combo) are designed to crush your guard and soul gauge as soon as possible, allowing you to do his... unique.. critical KO with more ease than say, talim who would be speed and techniqe.
I think thats really it. just get used to the new type of gameplay, as it is different from all the others.
on a side note, as amazingly customizable the create a characters are, and as kool as they look in battle, make sure your underwear isnt an embarrising colour, cause as soon as your lower guard is destroyed, you can wave goodbye to your trousers