So far, I like:
- Its ease of use. Check out hot tips: http://www.apple.com/support/numbers/hottips/
- Out of the box, you can use built-in templates that let you create financial statements, budgets etc in a few minutes -- no kidding!
- When you highlight a column of numbers, you instantly get sums, averages etc on a preview pane. Then just drag the formula you want into the appropriate cell.
- You can add sliders and steppers on any cell. They are like rheostats -- uhm, dials that allow you to increase a cell value up or down, automatically adjusting all other calculations. Nifty, tactile and visual!