Comparing it to VI, I would say the main difference is that V is more adventure-based whereas VI is driven by its story.

I wouldn't say the characters are any more shallow than VI's. If you consider having 1-2 sidequests character development (as in VI) then the characters are developed here.

Story-wise VI has it beat, although V takes a different approach, it's all fantasy.

Gameplay-wise I wouldn't compare them, V stands over VI with a somewhat flexible job system.

Music is great in this game, definately rivaling VI, i think this is where Uematsu started getting really good, Clash on the Big Bridge, Reminiscence, songs like those'll stay with you.

Personally I rate this game higher than VI, as I lean more towards the adventure-based FF's, but if you're just looking for a really good SNES RPG this may be for you.