Honestly, I have never seen a cartoon show more morals than Avatar. In the Waterbending Scroll, Katara learns that jealousy can get you into a lot of trouble. Also, she learns that above all, Aang's mission is most important and she can't needlessly risk it stealing a scroll to help herself learn waterbending. She invokes the wrath of pirates who will continue to cause grief.
We also hear for the first time about the White Lotus. Perhaps the reason why Iroh wanted to find his Pai Sho tile so badly was because he knew that he might need the Order of the White Lotus's help sometime. Also, we see than Iroh isn't as determined to find the Avatar as Zuko is. Zuko tries to hunt down the Avatar in a single-minded purpose while Iroh is more calm and doesn't devote all his attention to finding the Avatar.
All in all, the Waterbending Scroll is a good episode, worth watching.