I've tested Otixo's free plan that allows up to 2GB bandwidth usage per month and is otherwise identical to the paid plan. To use Otixo, you must trust it with access to all of your file storage services, so I connected it to my Box.net, Dropbox, Picasa, and SkyDrive accounts.

Otixo is a webapp, so there's nothing to download. The interface is straightforward: A tree on the left shows all connected cloud services, and lets you drill into each service. To the right of the tree, a large table lists the files in the folder you are currently browsing. It's the same setup as Windows Explorer and most other classic file managers, really. One thing missing from the UI is a usage gauge: Each service has a different quota, and Otixo doesn't make it easy to see how much free space I have left in Dropbox or SkyDrive (for example).

Copying a file or folder between services is as easy as drag-and-drop: I clicked a folder in my Dropbox and dragged it over to my Box.net account. The transfer was not instantaneous, but it was smooth. Otixo shows a progress bar in the bottom-left corner explaining what is going on, and at the end of the process, I had a copy of the same folder in my Box.net account.

Speaking of "not instantaneous," that's something that could be said about the Otixo experience in general. When you first click a new folder, it comes up blank with a large watermark that says "Empty." Only after you wait a few seconds does the folder's content appear. So while the interface itself is reasonably responsive, this per-folder delay makes things feel slow, not to mention momentarily harrowing.

Otixo's other highlight is cross-service search, the idea being that you can type something like "*.jpg" into the search box and get a listing of all JPEG images you have stored across all cloud services. This did not work well for me: When I searched, results came up only from Dropbox folders I've already browsed. Not so useful, because if I already browsed the folder, I am probably aware of its contents. This is a Dropbox-specific issue and will be remedied soon, Otixo says.