The series as of today consists of seven entries, with one more coming up this year for the Nintendo 3DS. Let us talk about why we love it what it is that we love most about the whole series or individual entries.

Spoilers ahead, I guess.

I've fallen in love with the series ever since the first entry. The mesh of Disney and Final Fantasy seemed genius, since Disney movies have always been close to my heart. I loved how the game, despite its basically light nature, turned to darker themes towards the end, leaving loose threads hanging at the end. And Donald and Goofy are badasses, period. This game proved that Disney characters can be as awesome as FF characters, if not even more awesome. Anyway, later came Chain of Memories. Oh GOD, Chain of Memories. Say what you will about the battle system (I still found it very deep and fun), but the story was so well written... There were moments when I just felt so helpless, because Sora really was forgetting everything. And Reverse/Rebirth was just crazy awesome Later on came the much anticipated KHII... I loved it and squeezed everything out of it. The story may not have been written as well as the previous entry, but it was still very good and the game really shines gameplay-wise. Bought 358/2 Days as soon as it came out. It blew my mind away, similarly to CoM. The way the story progressed allowed such character involvement, that the ending ends up as one of the greatest tera-jerkers in a video game I have experienced. Haven't beaten Birth by Sleep yet, I just started Aqua's story. This game basically uses the best elements of the series, adds some awesome stuff of its own, and basically the outcome is what is possibly the best KH yet. Haven't played coded yet, but what with the DS remake, I may soon play it.
The music deserves special mention! Yoko Shimomura has really outdone herself. Her work fits the series perfectly, with great, fun tracks for the Disney worlds, and darker themes for the more serious parts of the story.

So what do you guys love about the series? (note that this is an appreciation thread, so please do not use it to complain, or at least reduce complaining to the minimum)