One of the major reasons I held out using WordPress for so long was its reputation as a swiss army knife of a platform. So many software packages that claim to do it all fall well short of doing anything well.
It's important to know that outside of the thousands of plugins and countless possible configurations, WordPress can be a pretty simple CMS if you want it to be.
I try to keep my installations as clean as possible, leaning on as few plugins as possible. Usually 5-10 at the most.
The core of what WordPress does, it does fantastically. The content editor continues to improve with each release. Managing posts and pages is a snap. Drag and drop menus are super simple. Creating custom templates is a breeze.
The worst thing you can do for the experience of your client (in the WordPress dashboard) is fill it full of cruft from plugins. Many shady plugins which promise some 'great' utility come with the baggage of ads, unnecessary extra additions to the navigation and extra links in the top menu bar.
Often I've logged into existing WordPress sites for customers to find 20-30 plugins each needing updating, many with nagging alerts. Most of which are unnecessary.
So my advice is keep it clean!
Recommended WordPress Plugins
Simple and it works. Be sure to setup Akismet to stop spam enquiries.
Just install the plugin, run through the configuration and you're set.
Super simple way to add Google Analytics stats to the WordPress dashboard
A little hypocritical this choice, but this plugin allows you to do all sorts of great extra, creative things with content on any WordPress site. It's certainly not necessary, but allows you to take a theme from standard posts and pages, to incredibly rich layouts.
Best of all with ACE is how amazingly well designed it is. Most WordPress plugins are created by back-end guys, where this is an amazingly well designed and operating plugin.