Cloud Backup Newcomer
I've tried quite a few backup/sync apps over the years, including Sugarsync, Spideroak, UbuntuOne, Box, and Google Drive, but I still mostly use Dropbox, mainly because of it's decent cross-platform desktop and mobile apps and LAN-syncing features. Now there's a new contender, the snappily titled Copy. It has Linux, Windows, OSX 10.7+ desktop applications and Android and iOS mobile apps. Since I do not have an iOS device, or an Intel Mac, and rarely use Windows, I shall focus mainly on the Linux and Android apps in this review. Feel free to let me know how well the Mac and Windows apps work in the comments.
Copy is very much like Dropbox in many ways. It has a similar referral process except that, at least for a limited time, gives you 5GB for each referral which is a hefty size compared with Dropbox's 500MB. You can also get another 2GB for tweeting the referral link on the Copy website during their 'Tour'. Here's my referral link, which will give you 10GB initial storage instead of the 5GB when you sign up without a referral. With just a few people signing up with your referral link you can quickly get a decent amount of storage, I currently have 32GB as of now! Also like Dropbox and others, Copy also allows you to share files with others, though only so far through the web interface.
Linux Desktop App
The Linux app comes in a tar file and once extracted, the app runs from that folder, best to unpack it somewhere you'll remember it, then choose the appropriate architecture (32 or 64bit for your system). For a desktop system, (I'm using Ubuntu with Cinnamon Desktop) double-click CopyAgent and it asks for your account details and other settings. It automatically sets itself to start at login and runs like Dropbox and UbuntuOne do, with a little icon or Indicator. You can also set where you want notifications to appear (it does not use native notifications) and you can pause sync like you can with Dropbox. Also, like Dropbox, Copy syncs over local LAN to save bandwidth. You can set bandwidth limits and like Dropbox has Selective Sync, so you don't have to sync all the files in your Copy account (handy for small SSDs). You can also choose where you want the apps main folder to be, much like you can with Dropbox. You start with an empty Copy folder, apart from a quick start guide PDF. One thing missing with Copy on Linux is there doesn't appear to be much integration with Nautilus, there are no little emblems on the files and folders to show they are synced or syncing. It does create a bookmark in the side pane, but it appears as a blank icon for me. It's also possible to run Copy on a headless, commandline-only system using CopyConsole, instructions are in the Readme file.
The Copy Android app is a lightweight and simple to use and has image and document previews, though they are not as good as Dropbox's, which you can flick through like a slideshow, while Copy only lets you view them singularly. Copy's app works well though oddly my Android apks I backed up from my phone don't seem to appear in the mobile interface. Edit: They are showing up now. Other than that it works just fine on my Motorola Atrix 4G, LG optimus 2X and cheapo Scroll Engage tablet.
Copy's web interface is quite nice, clicking on Browse to view your files shows a folder structure that reminds me of the way Finder shows nested folders, and shows image previews much like the mobile app.
Overall I would say with a little more polish, Copy could be a good contender for Dropbox and it has certainly come along at the right time as my Dropbox is really rather full right now! Dropbox still has a few advantages like better integration with Nautilus and LAN-sync, and also though not important for most but handy for me, PowerPC Mac support! However for sheer size of storage, especially with 5GB referrals (at least for now, it's not stated how big referrals will be after this limited time), and having most of the features of Dropbox, Copy is winning me over.
Important Update 01/01/2016
Copy is being discontinued and I am not sure when I am going to put my accumulated 300+GB of files, I do not have that kind of storage in any other service, so i will have to rely on having it on 3 different drives on 3 different machines.