Its a problem with RPGs really as it basically defines the difference between a JRPG and any other type of RPG.

A linear game basically means its completely story driven and for the most part removes any choice the player has, it was a major problem I found for lots of early RPGs in the PS2 era. Story driven has the problem of being a really good experience or being a nightmare depending on how you feel about the plot. XIII sounds like it may avoid this so its all good but it makes me sad to realize that exploring for the first half of the game will probably net me a few minor items and be me just looking at the scenery as opposed to finding something new and exciting to divert my attention for a minute. For a genre that started on the foundation of exploration, its really moved far beyond its roots.