Spideroak user here. I stopped using Dropbox and started using Spideroak about a 18 months ago. I really like the product. It's not as good as Dropbox in some ways (like automatically syncing photos from my phone) but it really is easy to use. I still have a mobile client on Android and I can keep my files in sync across multiple computers. I pay for the larger storage size and I'm not even close to using it all.

It syncs fast too. Just thought I'd share my experience with people.