I've been a Dropbox user for several years, though I've always used their free service. They work for most platforms (currently I use it for Linux, Windows and Android) and it's been beautifully integrated with each and every system I've used it with.

My only problem with DropBox is that it doesn't offer as much security as I'd like to. DropBox has been in the media several times with security issues, and that is what makes me give them 4 stars.

Even though, I'm thinking about getting a subscription with more space. But I will never used DropBox to store anything too personal.

Overall a great product.