It's a great game and a lot of fun, and I hope they make more episodes, but with each episode being a different app to pay for and download with each chapter being really short seems a bit much.
When you go to the second episode you have no reason to go back to revisit the first episode, so I hope you didn't invest too much time in that episode 1 dojo because that won't matter in the next episodes. Any progress you made or anything you unlocked won't transfer over. It would have been better if they made it a bit more expensive and just had the episodes be updates. That way your progress is saved between the chapters and the new skills you learn can help you in the dojo and you can just unlock all these things once.
It's a great game and I thoroughly enjoyed it, but you might as well just get the most recent one and just watch replays of past episodes.