The only thing that bothers me about this is the fact that they have a schedule already for this DLC that only extends for about one month past release with the first pack releasing literally the same day. I'm pretty sure we collectively agreed in the past that day one DLC like this is bullshit and should just be included with the game to begin with. Look at this logically and realize that Nintendo would be taking this step eventually, but also consider the fact that this is a very poor implementation of the idea. The season pass isn't a deal. You are simply paying extra for content that Nintendo decided to omit from the initial release likely for no reason but to test this type of development and sale.
Edit: In fairness to Nintendo, I do have to acknowledge the approximately $10 less price tag on this game when compared to other first party title prices making the $15 DLC essentially equal out the price for other first party titles. Presumably, this was also part of this test run, keeping the price around the same place just to see if the season pass was an idea worth pursuing for them.
Realistically, they would be far better off sticking to individual DLC for each game right now, not worrying about packs and dedicated DLC release schedules when they barely have any experience at all with it. A season pass is a big step that shows dedication to one game for an extended period of time, and the way Nintendo develops doesn't seem to allow much for prolonged periods of time being spent on individual titles post-release. Considering they almost exclusively support both the 3DS and the Wii U, I have a hard time believing that their studios have time to consider season pass DLC while just trying to push games out the door fast enough to keep the dead times between releases shorter.
All that aside, their entire online system really blows, and I don't like the idea of even more paid content being tied to something like an NNID which is still tied to the system rather than actually utilizing an online based account system. Maybe they should consider getting their general service into the now before using newer DLC ideas like the season pass.