>>718039927
It fixes a LOT of the design problems that 13 had, regarding side quests and explorable areas and the 15 hour combat tutorial and the story being told out of chronological order (hugely ironic for a time travel game).
I think the best play order is 2 > 1 > 3. 2 first so you can get into the simplified combat system right away and explore, then one so you can get the story of how things got to where they were in 2 but with more background understanding, and enjoy the combat system at it's peak, and then 3 to wrap things up and get "town exploration" and more side quests and a fun and unique battle system.