I actually liked the question in the QBook, I thought that they were better than the QBank. The key to passing this exam and all the Steps are doing questions from different sources.
I thought it was pretty good but not great. Not as good as USMLEWorld, but a good set of questions for the price. Perhaps slightly better than the NMS question book (which seems to have fallen out of vogue but is also pretty good).
I didn't use QBank so I can't make that comparison.
Just in case anyone's interested, there's a new Qbook coming out in a few weeks and it's 1/3 off on Amazon. If you aren't in a rush, you may want to wait for it.