Yeah the story mode doesn't change much. Most of the DLCs focused on expanding Adventure Mode, which was the main section of the game tbh. Story was just mechanics introduction mostly. The additions they did make were decent tbh. Two new maps which are both fairly large maps and require the multi-character switching feature, two new giant bosses, one of which is extremely challenging because there's no obvious pattern given for it for the second phase (And there is always a second phase on that guy), a bunch of new characters who are extremely fun to play as (Other than Medli but she was free on wii u anyway), plus the extra story stuff. Which tbh is pretty decent. Cia's Tale is actually somewhat challenging in parts, and actually tries to make her a somewhat interesting character, whereas Linkle's Tale is just Linkle going around on cleanup and being awesome. Also Cucoos. Linkle has lots of Cucoos. And then there's the WW bonus ending stuff which is... alright. There's definitely highs and lows to it, but the final chapter of the WW addon is quite possibly the best story chapter design in the entire game (So much so that they recycled the base concept for the FE Warriors endgame).
Is it worth getting? Well, the DLCs alone probably total about sixty quid, with less download time and having to grind up characters. It's probably worth getting.
