If you have the finesse feat you will use your Dex to determine your to hit bonus, if it is higher than your str. Your Str will still determine the bonus for damage, regardless.
The finesse feat was a good idea in the D20 system for people who wanted to play Dex Fighters and rogues instead of a full plate clad warrior. I think it is a good feat for a Jedi as they are Dex Based fighters anyway. If you are a guardian I would still not ignore Str, though. As that class has to excell with a a light saber.
I think this feat is not a important now that Jedi can wear armor that lets them use their force powers.