I’ve been using MobileMe for a while to handle syncing of contacts and the like between two different Macs, an iPod Touch, and now an iPad. It works quite well for that, but the iDisk feature is sadly lacking. I use it to move small files between various computers (including my Windows desktop), but only for that limited purpose. If I try to move a file larger than about 1 MB it will at best take a very long time, and not infrequently will freeze up entirely. Leaving files that I need to have reliably available on my iDisk and opening files there directly are right out.
After seeing positive mentions here and there I decided to give Dropbox a try. The Dropbox interface is basically the same as iDisk’s–it puts a folder in the sidebar of Finder windows, and you interact with it the same as you do any other folder. Unlike iDisk, where you are connecting to a server, the contents of the Dropbox folder are stored locally and synced to the server when something changes.
Keeping files on the local drive makes it practical to work directly with files located in the Dropbox. Syncing also happens much faster than iDisk–for example, a 1.2 MB Curio file which broke iDisk when I attempted to upload it synced to Dropbox in under a minute. As a test I put a (roughly) 1 MB Tinderbox file that I use to keep track of all the builds I’m responsible for at work on Dropbox, and found that changes made on my Desktop Mac sync in the time it takes to walk the ten feet to my laptop Mac.
The current version of the Dropbox software on the Mac doesn’t preserve file metadata such as file type (for files with no extension) or Spotlight comments when syncing, but there is a prerelease version of the software on the company’s forum which does preserve the metadata–that’s the version I’m currently using.