Unfortunately, despite DataViz's claims to the contrary on the App Store listing, even this Premium version of Documents To Go doesn't actually edit PowerPoint files. Amusingly, if you create a new PowerPoint document within the app, you can add and rearrange slides on it, but you can't put in any text or pictures. If you tap the little triangle button in the bottom menu, however, the app will give you the option to open (and edit) your presentation in any other Office-compatible app that you have loaded. At first I thought I must have been doing something wrong, but the reviews on the Apple App Store are rife with criticism over this problem. It's almost certainly a bug, and I hope to see it rectified quickly. Otherwise I have to suggest that anyone looking for a way to edit presentations on the iPad should look elsewhere for that functionality (particularly given that even Documents To Go Premium looks elsewhere on your iPad for that functionality).
Where Documents To Go Premium stands out in a good way is in its cloud and sharing features. In addition to support for Box, Dropbox, Google Docs, iDisk, and SugarSync, it includes support for DataViz's Documents To Go Desktop App, which lets you sync files easily between the app and your desktop over a Wi-Fi connection.
Frankly, I had expected Documents To Go Premium to offer a far more compelling blend of features and performance than what it's delivering on the iPad right now. DataViz has had a decade's head start over its competitors in the mobile arena, but between the app's apparent bugs and its outright lack of common editing features, Documents To Go Premium is a big disappointment. There's simply nothing "premium" about it.
Quickoffice Pro HD
After a disappointing experience with Documents To Go Premium, I was looking forward to spending a couple of days working in Quickoffice Pro HD. After all, the Android version of Quickoffice Pro HD took top honors in my roundup of Android tablet office apps. Surprisingly, while Quickoffice Pro HD's iPad interface is somewhat nicer than that of Documents To Go, I found its editing capabilities sorely lacking--particularly in comparison with its overachieving Android-based sibling.
The editing menus in Quickoffice Pro HD for iPad are frightfully sparse--not in a sleek way that belies hidden power, but in a lame way that reveals low ambition. For instance, you can embed and format images in the presentation app, but not in the word processor. You can't create or edit charts in spreadsheets. The most robust part of the app is the presentation editor, which at least offers basic image-formatting capabilities.