I'm also one of those fans that loved Days, I myself love challenges and Days sure was a lot of training for a gamer of all consoles, the controls and the panel system... planning everything in advance because of your limited magic & items... time missions and endurance battles, bosses with ridiculously high HP and bosses with the real killer moves, now that was awesome for me >:'D and the story was over 9000 satisfying and of course I cried and it was New Year when I finished the game... Ah, symbolically perfect
but I agree that Days is a game for players with above average patience, if they really want to complete the game 100%
also, my third fav Keyblade is Omega Weapon from Days, I simply loved all the different Keyblades and abilities attached to them. Can't deny, I love Days, it's so much story, feels and challenge. The only thing I hated about it were the time-missions with "collect all the Organization emblems" . Now THAT was difficult.