That is some nice compost, but I've always mixed it into existing soil or added something to it. I've never tried growing in straight compost, so I don't know if it's a good or bad thing.
They also sell black dirt at the same place, as well as a mix of compost, black dirt, and sand. I think they call it "garden blend" or something close.
I'm also breaking new ground for a garden this week. My plan is to till the compost into the existing soil and adding aged horse manure to it as well.
Hopefully someone else will chime in with some advice.