As someone who knows the whole story and is a big fan of the series, I liked the plot of 358/2 Days. I just think the pacing was atrocious. I know it was meant to focus on day-to-day life rather than big exciting events, but that's no excuse for nothing happening for a full two thirds of the game. I get enough of day-to-day living in my real life, and there are only so many ice-cream scenes I can stand. The Disney sections offered very little relief, adding almost nothing to what we know about each world, thanks to the fact that Roxas for the most part avoids interfering. And Days could've used a lot more character development in the actual game rather than afterwards through Secret Reports.
That said, the gameplay is good solid fun, and I did enjoy playing it.