Hello,
My opinion on this issue would come across as a bit biased, I'm sure (check my name if you don't understand why that would be the case ;0).
Regardless of how you choose to prepare for the GMAT, most people benefit from some expert guidance. As such, each individual should do some research, sample the various course options (look for free classes, practice tests, tutorials, etc.) and find the program that best matches the individual's personality, time frame and budget.
You might even mix-and-match resources; I've read testimonials from many people who assembled a combination of books and courses to help them reach their goals.
GMAT assassins aren't born, they're made,
Rich
