Hi texdore,
It sounds like you're really interested in the convenience of not having to carry around a huge book (or a bunch of smaller books). Thankfully, there are plenty of options when it comes to GMAT resources.
Are you just starting out your studies?
What is your score goal?
When are you planning to take the GMAT?
Most GMAT Companies offer some type of free materials (practice problems, Trial Accounts, videos, etc.) that you can use to 'test out' a product before you buy it. We have a variety of those resources at out site (
www.empowergmat.com). I suggest that you take advantage of all of them then choose the one that best matches your personality, timeline and budget.
GMAT assassins aren't born, they're made,
Rich