Using a Rolleicord or Rolleiflex isn't hard. It takes a little bit of getting used to but, once you get the habit, no problem at all.
The thing you will learn when using a Rollei is to pay attention and to slow down. This will teach you to think about your pictures more.
There are often no meters. When there are meters they aren't coupled. No automatic settings. Everything is manual. You have to meter separately and consider all the factors before clicking the shutter.
Use your Rollei, exclusively, for a while then when you go back to using your Pentax, you'll suddenly notice how your photography skills have improved!