I have the EK review books for Bio, Gchem, and Orgo as well as the 1001 Gchem & 1001 Orgo. I wouldn't bother with the 101 Bio book because its all in passage form and not stand alone questions.
As far as how useful they are, it depends on how much review you need. They seem to be more conceptual and easier than destroyer. However, if you're having a tough time with a particular topic, the 1001 books make it easy because of how they're broken up. So if for instance, you suck at spectroscopy, you can go to that section and crank out a bunch of problems until it "clicks." HTH