As far as I know I haven't had any problems yet...actually, I went to try to set up that free trial account and Apple had already done it for me...it should work until Sept. 30 (I believe).
i had some trouble with Mail and .mac account. all i did was check that the box 'use authentication when sending mail' was checked. you'll have to go into prefrences and edit your account to change this.
Ok. Mine is working now. When I updated to 10.1.5 after my reinstall the other day, it moved all of my accounts around. Weird. It is working now so that is all that matters.