It looks like they've just launched and have similar base features to DropBox. Apps for iOS & Android + desktop installers for Mac, Win, Linux.
They are currently offering 15Gb of online storage as a starting point with bonuses for referring others - an extra 5Gb per referral. It's implied that the initial large amount of free storage and referral bonuses are for a limited time to create buzz and may be reduced later.
The one year of free 50Gb Dropbox storage I got with my Galaxy S3 will be expiring soon so I'm going to look at this as a possible replacement.
If anyone has heard anything negative let me know. The terms and conditions seem fine from the quick glance I've had.
Check it out here:
The above link will give you an extra 5Gb added to your account when you sign up - giving 20Gb free right off the bat. You'll get invited to immediately pick up another 2Gb by sending a tweet.
If you don't want to use a referral link go straight to http://copy.com to check it out (you'll only get the 15Gb instead of 20Gb when you open your account).
I'm always a bit suspicious about cloud companies that give away so much for free so interested in any feedback. With that said it's worked out extremely well for DropBox who did the same thing when they started...