It is literally my second favorite game of all time. Only FFVI beats it.
It's phenomenal. The music, the battle system, the characters, the graphics, everything about it is meticulously well-crafted.
Combat is similar to the FF IV/V/VI, but battles are not random. Also, max party size is three characters.
All of the extra endings are available in the New Game+. They tie into the time-traveling theme, but that's all I'll say...
The DS has some extra content, but it isn't particularly interesting. Just feels like padding honestly. I don't think any of it is available on the first playthrough anyway.
Don't use a walkthrough for the first playthrough. The game is very linear and you won't want anything spoiled. Also, it can be beaten in less than 25 hours which is nice and quick compared to today's bloated RPGs.