The Google Drive app lets you view and store files, spreadsheets, and videos, with 5GB of storage space for free, and more if you're willing to pay a subscription fee. The app only requires that you log in to your Google account to quickly access files and media stored on your Google Drive.
Upon launch, the app gives you a list of items to let you quickly get to files on My Drive, files shared with you, files you have "starred," recently opened files, and those you have made available offline. In my testing I opened and looked at a Google Docs spreadsheet, a text file, and a couple of images, all of which were viewable on my iPhone. While I could store an MP3 on my Google Drive, I couldn't play it, so if you were thinking this might be a way to stream music not already on your iPhone, you'll need to look elsewhere.
New to Google Drive for iOS is the ability to create and edit documents. In editing mode, you can change font styles and access other formatting tools. Also, you can now view presentations through a nifty slide viewer. Unfortunately though, Google Drive on iOS still cannot edit spreadsheets.
Another big addition is the ability to upload files right from your device, directly into your Google Drive account.
Those who want the ability to read text files and spreadsheets synced across different devices will find Google Drive useful. Plus, the "make available offline" feature will be a godsend to frequent fliers, as well as anyone traveling to a location with no Internet access.
There is still obvious work to be done on Google Drive for iOS, but I would still recommend it, especially for anyone looking for mobile Google Docs access.