Great Reporting Module
First, just a comment about my ratings. The only reason I have marked the module down slightly on ease of use and documentation is because someone at my level of competence (I am not exactly a Drupal genius) may possibly struggle slightly to get to grips with some of the facets of configuring this module. Once you have made it through the hurdle, it is actually very logical, and you will probably end up shaking your head, wondering why you struggled at all (like I did). But it does present a few little challenges if you are not reasonably competent.
That having been said, this module is simply marvelous, and if you want to put complex drill-down reports onto a website - derived from arbitrary amounts of data - this module will do it. And do it really well. And fast.
In addition, it will add competent and professional graphs, of various kinds, again allowing for graphing from arbitrary amounts of data.
I can recommend this module highly. I do not know what I would have done without it.