Should I finish FFXIII before beginning FFXIII-2?

Solution 1:

If you don't want the ending of Final Fantasy XIII to be completely and irrevocably spoiled, do not play Final Fantasy XIII-2 until you complete it: don't look at it, read reviews, play the demo, or anything.

Final Fantasy XIII-2 is a direct sequel to Final Fantasy XIII, and its entire plot hinges on the events at the ending of Final Fantasy XIII. That ending will be spoiled within 15 minutes of starting Final Fantasy XIII-2.

Solution 2:

I'd recommend it. Broadly speaking, Chapter 8 is where the last 2 protagonists stop running and accept their fate as l'Cie. What follows next is a revelation to their Focus, followed by their reaction to it. Given that FF XIII-2 takes place on Pulse, you may want to complete the story.

Solution 3:

Something everyone has missed in their answers is the fact that you can do a sort of "what happened in XIII?" replay thing where it shows you the basic story outline of FFXIII.

If your not interested in actually finishing XIII then you can just start XIII-2 and watch through this instead.

I'd personally go for finishing the first one, however if you really can't be bothered then this is a simply way to carry on yet know whats happening with the storyline.