The Rolleicord is easy to use. Some things about it would be different from what you are used to doing -- besides the obvious (reversed image; loading of 120 film), you need to wind and charge the shutter as two separate steps. And the shutter release is definitely different from the normal "push the button" as you have with your Pentax. But these are easy to get used to.
You will love the quality of the pictures. It's true that the Xenar lens, as a 4-element lens, is a "lesser" lens than the Planar or Xenotar of the later Rolleiflexes. But it is quite good indeed. As others have said, get a lens hood. I would recommend one of the Rolleinar close up lenses, particularly the Rolleinar 1, which lets you focus from 1 meter down to .5 meter. Very useful for closeups, including tight portraits. And of course you will want an exposure meter.