Granted, I wasn't able to go through all the questions, but I've gotten a good 'feel'. Here's an overview of the features:
More than 700 GMAT math/verbal practice questions
Every GMAT practice question features a video explanation for the given question, written/produced by a veteran GMAT instructor
Completely online practice - study at work or at home, without carrying books around
Ability to customize your prep based on subject area, with just a few clicks
Performance reporting to identify your strengths, weaknesses on GMAT subject areas
Adaptive practice algorithm that mimics the real GMAT -- the better you do, the harder the questions become in your practice session
30-Day Money-Back Guarantee if you're not satisfied
I am not going to waste too much time sharing my thoughts on the course. I love it, and i think it's well worth the $99. At the end of the day, all said and done, what really makes the difference between potential and how you perform on test day is how much effort you have put in. Not how much material you have covered, but how much you have practised. I'll try and explain this with a football analogy. I may know how to dribble, do a drag-back, nutmeg an opponent, play a long ball, but at the end of the day, what matters is how i use all these skills on match day. If i run straight into a competitive fixture having just practised the skills alone, I will end up looking like a bumbling fool. Only the hours I spend on the training field and friendly matches will help me star on match-day.
You'll have noticed that the last bullet point in the features overview is in green colour. Why? Because that's your signal to go for it. You have the option to try it and see for yourself whether you think it's worth your $99! Enuff said!
Edit*: Turns out there's also an ipad give-away. 3 ipads up for grabs! + limited time offer: $50 discount What are you still doing here? :D