Category = better than Taxonomy & book except for potential bugs and slow down of site?

So is it OK to say that Taxonomy and Book both do nothing that Category cannot do? And Category can also do some things that Taxonmy & Book cannot do, right? So the only drawback for Category is that it's buggy and may slow down your site, right?

If true, those facts would be very useful to have on the project page or frontpage. For example, - "If you are considering using Category instead of the core Taxonomy module and/or core Book module, know this: Category does everything Taxonomy and Book do and more. However, it may slow down your site and/or result in errors." If this is true, I suggest you take that quoted text and try not to garble it too much with words that casual users won't understand. If it's not true then I suppose I have more reading to do.

Anyways... documentation is seriously lacking with Drupal as a whole. Even Joomla documentation is better. :P