> They're also slowly cultivating a third party integrated apps ecosystem.
I think this is a big part of why Dropbox could warrant a high valuation. If Dropbox is simply "the platform" for file sync, then more integrated apps will come along with Dropbox support.
For example, the notes application I use on my Android phone (Epistle) uses Dropbox for sync. This is great because I always have those notes on my computer too. I think we'll see lots more of this in the mobile space.
And their stuff just works really well. They're also slowly cultivating a third party integrated apps ecosystem.