It'll take 50 hours to see everything in Lightning Returns

[Andromeda]

According to Square Enix, they have said on the average, players will take about 20-30 hours to complete a playthrough of the game. As explained earlier, there is a lot to see and do in the game. It is possible, but unlikely to do everything in the game. The game encourages multiple playthroughs to experience everything. They have said it would take 50 hours to do everything in the game. It is assumed they mean if you knew how to do everything correctly in a single playthrough.

For the new game+ your levels, gear and abilities will carry over. You can also change the difficulty. Likely, after being leveled up it the new game+ is going to be too easy. Those wanting a challenge will want to increase the difficulty.

Source: Lightning Returns: Final Fantasy XIII Takes 20-30 Hours To Clear - Siliconera

[Cyric]

I actually like the idea of a new game +, it just sucks they decided to implement awesome features like that on a game I have .014% chance of playing. I still haven't beaten FFXIII just because I couldn't get into it.

Also 20-30 hours seems a bit short. I know there are people that can speed through nearly any FF title, but 20-30 hours seems like they're making shorter games.