This program comes as an alternative to using the default methods (with the help of your default browser, of the official Dropbox app, or even of the default Finder app) to access your personal Dropbox account and manage its contents. The utility sits on your Menu Bar where you can enter your credentials and start checking the data you store in your Dropbox account.
The first thing I do when installing a program from the Mac App Store is to read the comments from users who used the utility in question. App for Dropbox's page was filled with negative reviews from many users.
First things first, this utility lets you use a small amount of its listed features. If you make an in-app purchase and upgrade the app to its Pro version, you unlock all settings (switch to desktop mode, ability to define global hotkey for revealing the main window, etc.).
Another negative aspect is the fact that even though it says on its homepage that you can upload files to your Dropbox account, the program fails miserably at completing the task. In my testing, I dragged and dropped a TXT file over the app's window and all it did was reveal the document's content in a separate screen. The file wasn't uploaded to my account.
Hence, the app only lets you check your Dropbox account and download files that were uploaded by you, from another computer or media gadget.
In my opinion, it's better to download and install the Dropbox app. This way, you can upload and download your files without encountering any issues and paying any money.