Google Drive for Android and iOS has been upgraded. Check out the Google Play Store or the App Store for the latest version that includes several new features. iOS users will get editing and Android users get several features including the ability to see and reply to comments.
Google Drive still needs better security. Dropbox's mobile app allows you to set a separate PIN so if your phone is lost nobody will have access to your files. Google has yet to implement this feature.
Google Drive:
Keep everything. Share anything.
*** Google Docs is now a part of Google Drive! ***
* With Google Drive, you can store all your files in one place, so you can access them from anywhere and share them with others
* Use the Google Drive Android app to access your photos, documents, videos and other files stored on your Google Drive
* Upload files to Google Drive directly from your Android device
* Share any file with your contacts
* Access files others have shared with you on Google Drive
* Make any file available offline so you can access them even when you don't have an Internet connection
* Manage files on the go
* Create and edit Google documents with support for tables, comments and rich text formatting
* Edits to your Google documents appear to collaborators in seconds
* View Google presentations with full animations and speaker notes
* Make quick changes to spreadsheets
* View your PDFs, Office documents and more
* Upload and convert files to the Google Docs format
* Take a photo of printed text and convert it to a Google document
* Print files stored in Google Drive on the go using Google Cloud Print
* Open files stored in Google Drive through Drive enabled apps in the browser
* Optimized experience to take advantage of larger screens for tablet users, Honeycomb (Android 3.0+)