I've been struggling with learning the basics of Drupal 7 and I've managed to get pretty far with my website. But one thing that bugs me is that it's a living hell trying to find what module does what and very often you need a primary module and then additional modules to make 1 task that a lot of times should be in the primary module.
I've been developing sites with Drupal for the past 7 years religiously, and almost ALWAYS deter clients from using Wordpress for their company site. There have been times when we've gone with Wordpress (against my recommendation) to handle quickie brochure type sites. I'd say that 90% of those have been hacked at one time or another.
There are a lot of D6 and even D5 sites in the wild which can't necessarily be upgraded in a timely manner. Historically, Drupal is not famous for creating workable upgrade paths from one point release to the next for various reasons, not the least of which being the drastic differences in how core is written and the contrib environment that grows up around these changes. This adds considerable expense to upgrading an old site, because you essentially have to spec the whole thing out fresh, build, deal with migration, and finally go through user training all over again.