[matteotom]

Unfortunately, there is no Linux client, so it is not a better Dropbox client for me.

And they did not indicate it was Windows only (with Mac support coming soon) until I signed up.

[ericmsimons]

From the front page of the website:

Starting with Windows, we let you access any file on any provider, all with a single login. Support for Mac, mobile and the web coming soon!

[chadnickbok]

We're working on the Mac and Linux clients at the moment; if you sign up, we'll invite you to the beta once they're ready ;)