I'm a big iWork fan. I think Pages and Keynote are two of the most underrated apps on OS X. Whenever I see someone get a shiny new Mac and immediately goes to install Microsoft Office on it, I shed a small tear inside.
Keynote is by far one of my favorite things about OS X. It makes presenting fun. I do a fair amount of presentations here at school, and I don't know about the "real world", but if you know a little bit about making presentations, it's incredibly easy to make a good presentation. Follow the 10/20/30 rule, don't add lame sounds, follow a goodish color scheme and already you're in the top 80% of all presentations. Once you do that, you can craft your presentation in Keynote and it becomes really easy to make a killer presentation. The transitions alone make things look good. The default templates are fairly attractive. Guides that snap objects in place, incredibly attractive graphs, and all the options in the inspector panel help seal the deal. Keynote is a supurb product.
Pages is likewise quite good. Word has never really been that great to me. I mean, yeah, it's a word processor. But Pages fits better for me. I know it's been said that most people only use a small portion of the functionality of Word, but they throw everything in there to satisfy everyone. Pages just simplifies things for me- I don't need all the minute detail that Word can get into. Admittedly, I know this isn't the case for everyone- with Pages it really depends on how you use your word processor. It does give you the traditional OS X experience, so to speak: the integrated system-wide font menu, a nice templating system, a really solid table of contents and footer/header system, and (as with Keynote), the ever-helpful Inspector panel, which lets you get into different formatting options like shadows, spacing, colors, gradients, and all that fun stuff. A number of the features might have counterparts in Word, but it just feels more simplistically presented in Pages.
There are some drawbacks, though; interoperability with Word and PowerPoint files isn't 100%. There are still a few glitches I catch here and there, though for the most part I think Apple's done a pretty solid job. And the most glaring problem is that you still need Office for Excel- there isn't an Excel replacement for iWork yet (which hopefully will change eventually). But it brings the Apple-esque feeling to the more mundane parts of computing, which is sorely lacking in other software packages out there I've found.