More than just a cloud storage solution, Google Drive has a built-in editor for making changes to your documents on the fly. The app even lets you create new text documents or spreadsheets and collaborate with other users by editing a single document with them in real time.
Google Drive's Documents editor offers a handful of formatting tools to help dress up your text. In the toolbar at the top, you'll find basics like lists, bold, italic, and underline, as well as a font tool that lets you change text size, color, and style. Meanwhile, the Spreadsheets editor gives you similarly useful formatting tools, plus extras that let you change the color and alignment of cells.
When using these editors, it's important to remember that they're not meant to be full-fledged offerings that are on par with their Web-based counterparts. So, for instance, you won't be able to change line spacing in your text documents or mess with formulas in your spreadsheets. Still, the built-in editors are good at the basics and should suffice for most of your handheld needs.
Similar to the Android version, Google Drive for iOS doesn't let you edit presentations or drawings. It lets you view these file types, but there are no tools make changes.
One thing I think the Google Drive app needs is a password-protect feature. As it is now, anyone with your device can easily fire up the app and tap into your private files. Dropbox currently offers this, and it would be nice to see Google come loaded with the extra security as well.
Regardless of its (few) shortcomings, I still highly recommend downloading the Google Drive app for iOS. It nicely integrates a good chunk of document-editing functionality, with its powerful Dropbox-style storage.