How do you organize Final Fantasy?

[Vincoletto]

AZWification said:

Vincoletto said:
Also I like this:

The Good: IV, VI, VII, IX, X
The Bad: V, VIII, X-2
The Ugly: XIII, XIII-2, XIII-3
The unknown: I, II, III, XII

Well, it's a great thing Final Fantasy II remained unknown!

Why is that? I heard the game is VERY hard and changed some stuff from the first game, but apart from that, any specific details?