Doing calculations is just as easy. Common functions are immediately available from a menu in the toolbar, and many of them automatically act on the numbers in the column of the cell you assign them to. For example, if you select a cell at the bottom of a column and choose Average from the Function menu, the cell will average all the cells above it. You can specify specific cells to include in a function as well, and as in Excel, you can do so by just clicking each cell -- no need to type the row and column number. A particularly nice touch is that the functions are aware of the column headers, so that rather than reading "=AVERAGE(C2:C9)," the cell's value will read "=AVERAGE(Math Test)" or whatever.
If you do need more advanced formulas, there are more than 150 functions that you can use, all of them comparable to their Excel counterparts (which is great if you open an Excel file or need to export for Excel users). None of the engineering and database functions available in Excel are duplicated in Numbers, however, and only about half the statistical functions have equivalents. (For a fuller breakdown, check out the list compiled by blogger Jaime Curmi.) Furthermore, the pivot table feature is not included in Numbers. As a result, serious number crunchers may feel more than a little hemmed in, and any longtime Excel user will probably need some time to get used to the new graphical world that Numbers offers.
One easily overlooked set of features is in the Sort & Filter Panel, which allows you to not only sort data in a table but also filter the results. In this aspect, Numbers behaves almost like a database by letting you see only data that you want (transactions before a given date, people who have confirmed to attend an event, bills that are unpaid, invoices over a certain amount and so on). The process of setting filters -- basically the familiar Mac approach of choosing search criteria from pop-up menus -- is much easier and more capable than performing equivalent tasks in Excel.
Speaking of Excel, Numbers can easily open Excel files. For a number of the Excel documents I've tested, Numbers invited me to review minor warnings after opening them, mostly dealing with formatting issues and one or two formulas. And in some cases, heavy calculations in an Excel document that I opened in Numbers seemed to take longer to process than they did in Excel or in a similar document created from scratch in Numbers, even after the Excel document was saved as Numbers file.
Numbers also exports well to Excel. Each Table in a Numbers document becomes a separate worksheet when exported, and the first page of the converted document presents a summary of which Tables were converted into which worksheets. Images included in a Numbers file, as well as any charts, are placed on a separate worksheet as well. Other text content and much formatting are lost during the export process, but comments are preserved. Numbers also supports export CSV files for use in other spreadsheet applications or databases.
Show Print View is another great feature it would be easy to miss. Not only does it show you how your current sheet will print, but you can directly edit anything while in it. You can resize or filter a table to fit on one piece of paper, move a graphic or change styles, all on the fly and while seeing how changes will affect the output. You can even edit data or formulas.
One final cool thing that I have to mention is the way Numbers integrates with the Mac's Address Book. You can drag individual contacts or groups into a sheet and they automatically format as a table. Or, you can create a table and name the column headers to match specific fields in Address Book; when you drag contacts to that table, it will fill with only those pieces of contact information. It's a perfect way to manage contact lists, guest lists, mailing lists and even invoices.
Overall, Numbers can truly be thought of as the spreadsheet for the rest of us. It may not be perfect for replacing Excel in every situation, particularly in corporate environments that rely on specific functions that are not included in Numbers. But for home users and small businesses, it is a great and inspiring tool and is alone more than worth iWork '08's US$79 price tag.
Users comfortable with Microsoft Office may find it takes time to get used to iWork. Advanced Word and Excel users, especially those who rely on specialized features and functions, will probably find Pages and Numbers to be limited. If you do rely on specific functions in Excel or features in any of the Office applications that are even slightly outside the more general types of usage, you will probably want to download the iWork '08 30-day trial to ensure that the tools you need are there before buying. And, to be sure, the process of having to export files when interacting with Office users could get old quickly if you have to do that regularly.
But overall, iWork '08 is beautifully designed -- a compelling product and great value for consumers and small business alike. It brings tons of innovation over previous versions of iWork as well as many office suites on the market. And it turns typical office tasks and documents into creative outlets. That it offers all that it does for US$79 is, frankly, hard to believe.