Laseander
Honorable Pirate
This thread has a lot of good points...I personally think the right answer lays somewhere in between -- leveling some before you quest will be a lot more efficient than being a jack of all trades. However, letting yourself become level 25 before you even start the Black Pearl quests at least makes the game play in a way that was unintended, and at most can give you issues with getting the XP you need.