I don't really think endings are that important, the game is the journey rather than the destination, and I had a lot of fun with it. Even if I never finish it, when I look back I'll see a game I really liked playing instead of a game that I never finished. If I start grinding levels for the final boss, I'll look back on it as "that game I had to grind a lot in" which is not a memory I want to have.
If you like I can do a write-up for the pre-final-battle cutscene, but nothing really happens. Well, I guess we finally get to hear their motive, but it's not exactly a shocking twist or anything.