To create word documents, spreadsheets, and presentation files, you can purchase Apple’s apps - Pages, Numbers, and Keynote - but these are to be downloaded and installed separately. That’s pretty much the disadvantage of Apple productivity apps - Each app has to be installed separately. This means that the apps for word processing, spreadsheets, presentations, and others, have to be installed one at a time. This will be a test of patience for iPad owners who do not want to wait.
But then, there are alternative all-in-one apps, including word processors, spreadsheets, and presentation apps that iPad owners can download as a bundle. A prime example would be QuickOffice Pro. For only $19.99, QuickOffice Pro allows you to make and edit documents, make presentations, and use spreadsheets.
A much cheaper option would be just to have a document viewer app and a simple note taking app or program. For this, all you have to install in your iPad is the GoodReader app ($1) and Evernote (free).