"Final" can be a rather subjective term.

Final Fantasy 13, among both new comers and long time fans of the series was reveived somewhat negatively.

Among the complaints about the game the most common where:
* The over simplified combat system
* The un-likeable main character (or lack there of, as some put it)
* The generic supporting cast, one of whom was a borderline offensive racial stereotype
* The story was incredibly convoluted (even by JRPG standards)
* there was a huge explanation of the setting but it was just text (a LOT of text) you could choose to read if you found it in the menu system
* The game world was incredibly Linear, removing virtually any element of exploration
* Vanille, arguably the worst character in anything ever.

A great deal of the complaints came down to personal preference, but it happened that a lot of people had the same personal preference. But it seems people were perhaps too quick to judge the game, FF13 was never planned to be a stand alone title.

Enter Final Fantasy 13-2, a continuation of the ill-received story. They had two years to learn from their mistakes and try to salvage the FF13 franchise and not only did it vastly improve on virtually all of the qualms of its predecessor (as any decent sequel should) it actually managed to justify some of the issues being in the previous game in the first place. That's right, the sequel did not just improve upon the first game, it actually improved the first game itself.

The simplified combat mechanics of the previous game were justified in that they were essentially an introduction to the new system, which was used in a more in depth way I'm the sequel. We could use the new system better and in more ways because we already knew how it worked from the previous game.

The characters were all expanded on in the sequel, which gave us some insight as to why they were the way they were in the previous game. This is especially true of the main character, Lightning, who was one of the biggest issues people had with FF13.

The story was told in a much more engaging way. The plot was just all around better and much more interesting and as there were only two main characters we got to know and understand them much better. The cast of FF13 was also there but they played secondary roles and we learned more about them through their interactions with the new characters.

Vanille... remained awful, but there was less of her.

This can of course go either way, a fairly solid argument can be made that we shouldn't have had to wait for a second game to get an understanding of the characters. But at the same time we knew beforehand that this was not the final instalment of the FF13 franchise.

Although one of the main issues that the first game had could not be excused. That being that so much of the story and setting details where given in an optional and dull text format.
A video game is an interactive visual medium and the general rule of thumb for all visual mediums is "show, don't tell" and they broke that rule pretty hard.

FF13-2 is a great game, a lot of people may have been deterred from playing it based on its predecessor  but again, FF13-2 is so good that it also makes a previously sub par game good as well.