Is it any good?
If you work it I think it helped me. By work it I mean that I found it to be most useful by doing the following:
For my second pass through I would work through each topic individually. I would start with just the basic questions for a topic. Once I felt good at this level I would step up to the intermediate level questions for that topic, and then the advanced. I found that each topic was different but by and large the basic questions were many and were way to easy. There were less of the intermediate questions but these were on point. There were even less of the advanced questions and I found these to be too technical. Do not use Qbank in place of the CFA text EOCs and do not use it to get used to the item set format. I think it works best as a drill to get concepts into your head, once you get through the Qbank questions (for me I would typically do 25 to 50 for each topic at the easy level and then all the intermediate and advanced questions it had for each topic - probably another 50 questions in total) then move on to the CFA text EOCs as these will be closer to what you will see on the exam.
In all I found it helpful (not as helpful as L1, but helpful nonetheless). But it should not be your core, if you are short on time and need to drop something I would likely drop this first, but I did find that it added value in helping me bridge the gap from reading the text and notecards to a level where I could start to tackle “real” exam like questions.