iWork is Apple's answer to Microsoft Office, it is relatively new to the market with just a couple of iterations but has the usual Apple look & feel. It is only available for the Mac OS X operating system(s), and has it's own proprietary file format, so doesn't work seamlessly with Office out of the box - although can be made to do so, just takes a couple of extra steps.

There are three applications within the iWork suite - Numbers, Pages, and Keynote.

Numbers is the spreadsheet application; the essential functions are the same as Excel, although Numbers attempts to do things in a more stylish way! You start off with a blank canvas, and then draw on cells & chart and position them wherever you want on the page. Initially this approach seems a little confusing, especially to those used to the endless cells of Excel, although in a way it makes more sense - you only draw the areas that you want, meaning that charts and cells can easily be positioned next to each other on the same page. The graphs look wonderful when compared to Excel's, with many fancy 3D effects available it is clear that this didn't escape Apple before a trip to the design department, there is actually colour's in the default themes - which I'm sure anyone will agree is a welcome change from the endless black & white.

Pages is a bit of a cross between Word & Publisher - said to be a desktop publishing application, but having the structure of a word processor. The overall layout is similar to that of Numbers - in fact it is a constant between all of the applications. It works well as a word processor, and has other integrations with apps such as the ability to embed "spreadsheet" objects, from which you can create graphs that will dynamically update. The DTP aspects of Pages are useful in that the allow for you to move object's such as images and graphs wherever you want around the document - removing the restrictions that Word often has, in addition to this it also has "guidelines" which appear allowing for you to easily centralise objects, something which I think is missing from Word.

Keynote is like a grown-up PowerPoint, replacing those cheesy slides with smooth 3D transitions, and comes with more professional looking templates. Essentially it will perform the same functions as PowerPoint, but also comes with some extras. A notable one is a dual-screen mode, allowing for you presentation to be shown on a projector while you get an overview (i.e. notes/next slide) on a second display - this can also be used with a separately purchased iPod Touch/iPhone App. Also you are able to export your presentation in a variety of formats, including a movie mode, allowing you to export it to a single video file to be played anywhere.

As I have mentioned compatibility with Microsoft Office isn't excellent, although it can be improved - Google "iwork 09 plist .doc" and one of the first results is an explanation of how to make Pages work with .doc files more easily, this greatly improves functionality and makes exchanging files a simpler process.

I'd say that iWork is much better than Office for Mac, it integrates much better and runs more smoothly, despite this the fact that it has tried to set it's own standards rather than adopt the file formats of Office is something that will deter many, but it is available for a free trial from Apple's website, so you can try before you buy.