When Bitcasa arrive on the file-syncing scene, it enticed users by offering "unlimited storage" for a reasonably small annual price—$69 during a promo phase, which has since been raised to $99 per year. The offer is compelling: unlimited storage, unlimited file-version history, chat, and email support are all included. The free account isn't shabby either, giving users a whopping 10GB, no questions asked.

So far, so good for Bitcasa. But for a file-syncing service to really win me over, it has to have a great mobile suite of apps. In testing, Bitcasa's iPhone app (free) was compelling to navigate and explore, but it also turned up a few bugs (all related to photos, by the way).

I love the interface, which gives you two ways to explore the content in your account. I love the speed at which Bitcasa plays music natively, and the quick-jump music button to bring you back to the player if you navigate away while a song is on. I love some of the little extras in the settings, like the ability to clear the image thumbnail cache as well as temporary files in your account.

As a longtime user of both Dropbox and SugarSync, I'm not necessarily in the market for a new file-syncing service, although anyone who is should definitely consider Bitcasa, especially to make use of that free 10GB of space.

The Basics

The Bitcasa iPhone app looks like no other file-syncing app I've seen. The interface shows "My Infinite Drive" at the top, overlaid on a storage device icon with a small arrow next to it (see the image and slideshow). Click this area, and Bitcasa whisks you away to a folder view of your account. Accessing files in this manner is straightforward and works extremely well for highly (organized people). But what if you're not so organized? Well, back on that home screen, you'll see a few sections beneath the "infinite drive" for photos, music, videos, documents, and favorites. Tap any of these areas, and you'll see only content in your account of that file type, no matter the parent folder of each piece, plus thumbnails when appropriate.

Bitcasa's display is categorically different from the Dropbox iPhone app, which shows your folders in a main view and much smaller icons for images and favorites only. Likewise SugarSync's iPhone app shows folders as the main way to access your content, with an icon to see just images tucked away in a collapsible left menu.

But wait! Bitcasa also has a collapsible left menu, and it too offers yet another way to get to your folders, or just your photos, or just your music, and so on and so forth. More handy dandy buttons in this tray bring you to the settings and a list of file activity.

A sucker for settings, I liked some of the options to explore in Bitcasa. There's an auto-upload setting for iPhone images, a PIN lock feature, and a snapshot of how much space you're using of the total available space—applicable to free users, as paid members get "infinite storage." But all the major file-syncing mobile apps have those features.

Some specialty options: You can "manage local storage" to clear the various caches that Bitcasa keeps, including thumbnail images and temporary files. Below the clear cache options are readouts of how much space each of the caches consumes. Data enthusiasts will love this stuff. You can also disable thumbnails from being stored at all. Sure, these are deep settings that plenty of users won't ever even bother finding, but some geeks will appreciate them.

Minor Bugs With Images
When it came down to really testing Bitcasa's iPhone app, the service acted a little buggy, I'm afraid. For starters, I uploaded a .jpeg image via the Web portal. At first, it didn't appear to be in either the Web account or the iPhone app, even though the upload seemed to go fine. So I changed the file extension to .jpg (deleting the 'e'), uploaded the image again, and refreshed the app and website. Eventually, the thumbnail of this image appeared as the album cover in the iPhone app, but the image itself was still missing from the list of files. Bizarre.

Another problem I had with images was down-sampling on the iPhone app. A reasonably large image file that I uploaded appeared blurry in the iPhone app, especially as I zoomed in on it.

Videos and music uploaded to Bitcasa can play right in the app—and they did without a hitch in testing—which is sweet, though not unique.

Dropbox, IDrive , SugarSync, Box—all these apps and others can stream and play music. Box actually downloads music and plays it via QuickTime, but it's a seamless and fast experience. Box and IDrive let you download music directly so you can play it while offline rather than stream it (or transfer it via iTunes).

Collaboration
When I'm out and about and unexpectedly need access to a piece of writing I have in progress, I usually want to edit it, and the lack of native editing capabilities in Bitcasa's iPhone app (and really most mobile apps for file-syncing services) is the number one thing holding me back from using the app more. I very often keep working drafts of articles in Evernote (the files are Evernote notes, not .doc files or another standard) instead for this very reason. Evernote is a very different kind of tool than Bitcasa, of course, but there are times when I wish Bitcasa had Evernote's capabilities wrapped into it. Luckily, Bitcasa works very well with other apps, including Microsoft's Office Mobile, so you do have the option to edit the file.

Dropbox probably supports integration with the largest number of other services, though Box is up there, too. Bitcasa is too new to hold that claim. And that's no small point. If you're using your iPhone for productivity, you need a clean and reliable workflow, e.g., store all your files in a file-syncing service that has an iPhone app, to which you can connect the office suite of your choice for actually doing something with the files.

If you want native editing, as well as collaborative editing, you want Google Drive (formerly Google Docs) or possibly Box. But there are problems with both of those options. First, there is no Google Drive iPhone app, only a slightly disappointing iPad app for Google Drive. On an iPad you can use mobile Safari to access the full Google Drive site, but iPhone users still have it slightly rough due to the small screen size. The problem with Box is that editing and document creation is supported in the website, but not on the iPhone app. One neat collaborative feature in Box, however, is the ability to add comments to any file right from the little iPhone app. If you can't actually edit the file, at least you or other collaborators can append a note to it.

Bitcasa
If you're in need of a new file-syncing service, Bitcasa's free account, with 10GB of storage, is a pretty sweet deal, although Box matches that amount (and has an exhaustive list of services with which it integrates). You only get 2GB with Dropbox, 5GB with SugarSync and IDrive. (For more file-syncing comparisons, see "The Best Cloud Storage Solutions.")

If you'll be using the mobile app a lot, Bitcasa has an interface that I think appeals to people who keep a lot of media-rich content in their file-syncing accounts, mixed in with regular old office files. I'd caution you, though, to keep an eye on problems with images.