Final Fantasy, i have never played it.

How many Final Fantasy games are there in the series, and would it be stupid to start at one of the later games? Because i believe the earlier ones are on PS1 so im not going to be able to play them. I saw a trailer and it looks kick ass, what are the objectives of the game and how much fun is it? Im looking to widen my genres of gaming.

Thanks for all help and knowledge that is given.