No, I'm not referring to the fact that and does not provide a mobile app client for any of the other platforms. Certainly, this is a factor for people who rely on iOS, BlackBerry, or Windows Phone mobile devices, but Google Drive can still be accessed via the Web on these platforms if necessary.
Robb Henshaw, Director of Communications at , explains, "One reason we believe the average user will have trouble with Google Drive is that it requires users to convert their files into the Google Docs format if they want to work on their files."
Users can upload and store other file formats like Microsoft Word *.docx documents, or Microsoft Excel *.xlsx spreadsheets, or PDF files. If opened locally from the Google Drive folder on a Windows or Mac OS X computer, those files will open in their native applications. However, if accessed from the Google Drive website, the files are opened as read-only in an online viewer.
In order to edit a file from the Web, the file has to be exported to--or saved as--its equivalent Google Docs file format. That process results in having two of the same file in Google Drive--the original, and the Google Docs version.
You can tweak, edit, and otherwise modify the Google Docs version from the Web, and those changes will be saved to Google Drive in the cloud, and synced back to the Google Drive folder on the local system. This introduces two potential issues, though.
First, the file that is synced to the local drive that has the most recent updates and edits will be in Google Docs format. Google Docs files in Google Drive are actually links that open Google Docs for editing online. If you happen to be offline, those links in the Google Drive folder would be useless.
There are a couple of ways to work around this issue. First, you can configure your Google Docs for offline access, and you can use Google Chrome browser extensions to enable you to edit Google Docs files offline. Another solution would be to save the file back to its original format after editing it online so that it will open locally in its native application as mentioned above.
That brings us to the other potential issue--file fidelity. Google has gone to great lengths to maintain formatting when converting from Microsoft Office formats to Google Docs and back again, but it still leaves a lot to be desired. For basic documents that just have text, with maybe some bold, italics, and underlining, or simple bullets, it may not be an issue. However complex documents that include things like a table of contents, footers, headers, and footnotes are likely to get mangled and require a lot of manual repair when switched back to their native format.
Businesses and consumers that already work predominantly with Google Docs need not worry. It will just be business as usual. But, those who may think twice about using Google Drive due to the need to convert to Google Docs formats to edit online.
Ultimately, cloud services from Google, Microsoft, and Apple tend to be more proprietary, and make the most sense for users that already work in a Google, Microsoft, or Apple-centric environment. For broader cross-platform integration, the more independent offerings like Box, Dropbox, and SugarSync may be the better choice.