Very accurate.

I subscribed to the gmat club tests a few days before the exam and was surprised to see how accurate the content was. The questions were very similar to what I received on the actual test day. The quant tests were more accurate than the verbal ones and I mainly used the quant tests. The quant questions are however consistently harder on the gmat club tests than the real test as in the real test the questions go from medium hard to hard depending on the test taker's capability. For me this was a good thing as I made a lot more mistakes during my gmat club quant tests and going through the solutions later on really helped strengthen my concepts.