hi Sahil......
I have been studying from it the last 7 days... so far so good. I like the structured feeling... even on my bad study days I feel that I have accomplished something only because I'm going with the schedule of the book. The scheduled questions for each day are very doable..
I am doing Kaplan and UsmleWorld questions too... I cannot say that the USMLE Step Booster has improved my score on UsmleWorld yet... maybe a few questions... but I am sure it will help me after I'm done with it.
in short: I do not regret spending $25 on the book... it's money well spent!