It more than just works. It works awesomely across multiple platforms.

It's simple (automatic) to use but not simplistic. Its power ramps up when you need it (file recovery) and fades away when you don't.

It doesn't get in the way (with advertising, installing crapware, charging micropayments, proprietary restrictions/formats, etc.)

Couldn't have said it better.

I think this was pretty shallow analysis by the author, but to his very first point - I do think it's the elephant in the room for a lot of startups. One of the most consistent pieces of advice/feedback I've heard from serial entrepreneurs and VCs is to stay razor focus.

Multi-platform is key. Shared folders can be used to collaborate not just with people, but with Linux servers too. I let users send files to my site by sharing a folder with it. I predict a lot of services will do that in the future. It's an easy way to give people offline functionality.

It might work "awesomely" one some platforms, but the Nautilus integration is pretty buggy - it was a nightmare to try to get it working on my Ubunutu 09.04. I ended up having to just use the command line utility a user wrote.

Odd. I had no trouble on Ubuntu 9.04.

Seriously. I left a comment on the host blog observing that points 2, 3, and 4 are basically the same, and can be summarized as: it's insanely easy to use. I set up Dropbox in about 20 seconds, and it did exactly what it said it would. Compared to every other synchronization tool I've ever used, Dropbox wins not by meters, but by miles.

My MOM uses dropbox.. even my dad does.

However, for me it's not so much a sync tool than an auto backup / versioning / web access to your files.

Dropbox works fantastically well with Keepass, just save the .kdb file in your Dropbox folder. Open up Keepass on another system and there are all your password once you wenter the master password.

I'm probably preaching to the converted, I'm sure most people who frequent ycombinator know about that but I still thinks it's once of the best uses for it so far along with backing up critical files.

It's also one of the only online services where I actually am strongly considering subscribing and paying money to upgrade once I approach the 2GB limit.

And it couldn't have been easy. I can think of a dozen features I'd like to see added, but most of them would only appeal to all small subset of users and ALL of them would make the service more complicated.

Until they publish accounts we don't know if it's thriving. They could have 2million free users all using 1.99gb and no paying customers at all.