Considering the options available to a series of this nature and the
scope of what's involved, as well as the passage of time, there's a lot
of really good stories that can be told when you need to break from
directly adapting the manga. The lack of such stories has been the most
difficult thing in dealing with these filler episode since they have so
much potential that's being wasted. Stories of ostrich ninjas only adds
insult to injury. So when we get an episode that takes us back to the
earliest time when Naruto learns of the Akatsuki and Jiraiya offers to
teach him how to deal with the special genjutsu he'll have to face,
interest rises considerably.
With Naruto having lost Sasuke and being frustrated with himself over it, the need to learn more skills and attacks is paramount, so having both him and Jiraiya go and train makes perfect sense. It's an interesting period for Naruto as he's got some serious issues going on because of Sasuke and there's a lot of pain there under the surface, some of which we see a little bit, but he's also still in the light and silly mode that's so regular for him. For Jiraiya, it's also a time when he has to feel somewhat nostalgic as he trained the Fourth Hokage and we know now about the lineage involved there. To teach the son of the Fourth Hokage, who has such a challenge ahead of him because of the Nine-Tails, has to mean a lot to Jiraiya and it explains so much of why he's taken to him and spends as much time with him as he does. When he's not chasing women at least.