i had the demo for around a month last year....the workflow is great, so is the mastering section...wasnt to keen on the mixing side of it as no matter what you do the faders are pretty small...though you can do small increments with your mouse wheel...
the instruments were kinda sucky but the effects were very very good...on par with my sonar
If i ever bought a new interface id go with presonus just to get the discount/upgrade you get from studio artist ownership
i have never tried cubase but i think Studio was designed by an ex cubase programmer so there is some similarity