Back when Dropbox was new, several friends pushed me to sign up for it. It's totally awesome! So easy to share files! Blah blah blah.
I was a little skeptical.
But I signed up anyway. And I used it for a few months before eventually discontinuing my use of it. I had a handful of problems with the service, both technical and non-technical. For starters, they are closed source. I have a big problem with that, mostly because I have spent my career working on open source software and have a personal problem with companies who take work that I likely helped along the way at some point, offer some sort of service, and don't contribute code back. I don't care that they charge for the service, it's the fact that they sit on their changes as some sort of secret sauce that no one else can have. Intellectual property lawyers and open source advocates have a long way to go before they understand each other, but let's say that Dropbox sits on the traditional side of the argument. I sit on the other side.
They offer a client for Linux and other platforms. The Linux client (at least when I looked at it) amounts to a small executable that they downloads a gigantic amount of unnecessary software and crams it in to a hidden directory in your home directory. It's basically like an entire Linux distribution just for running Dropbox. This is completely unnecessary and ties back to the fact that they are not open source. If they worked with the Linux community, they wouldn't have to invent these stupid hacks to work around what they perceive as problems on the Linux platform. "But all distributions ship different shared libraries!" Yes, they do. So open source your damn project and let the distributors incorporate it in to their distribution. They will do all of the ugly work of integrating it in to their platform. Companies still don't understand this and instead sign up for doing the annoying work on their own.
"But they are open source," you say? Oh, you mean this. Yeah, that's actually not really required to use the service and does nothing by itself. That is just the Nautilus plugin that communicates with the Dropbox backend software. It implements the drag-and-drop functionality for GNOME desktop users. You still need the binary-only blob that is downloaded and installed automatically when you getdropbox.
OK, so enough of the technical arguments. Dropbox is about easily sharing files with people on the Internet. Like you share files in your office maybe. And it does this well. Across platforms. But Dropbox has decided that it is going to declare itself a publisher rather than a common carrier. It's a tricky business that they're in. Is it ok to facilitate sharing files among people you don't know and then wipe your hands clean and say you're just the common carrier, like criminals using phones but the phone company not being responsible for any part of facilitating that crime? Napster tried to be a common carrier and lost. Of course, their service specifically was for sharing music with the unspoken selling point being you can avoid paying for CDs.
What about Megaupload.com, that site that no one knew about until the FBI raided the offices and founder's home...in New Zealand. They were more similar to Dropbox than Napster and the US government was still able to go after them, with questionable legal power and jurisdiction.
Dropbox is now scanning files you drop in your box for any content that may violate the Digital Millenium Copyright Act. Their legal team likely advised this as being the best mode of operation now given the legal action taken against other companies in recent times. But is it right? A topic for a law school exam, but I personally don't think it is sustainable for content enforcement in this capacity to be fair or equitable. It's already unfair and it will only get worse. The RIAA and MPAA need to come up with a new model for copyright ownership and revenue because the models of the past do not work in a world where I can download and watch Pacific Rim on my phone.
I had a feeling that Dropbox would eventually start doing this if they weren't already. Do you mind your files being scanned by a company? Do you have private data stored there? Unless you have total control over the system you're storing data on, you given up privacy. Maybe that's ok for some people, but do you really feel ok knowing that ANYONE at the service provider has access to your data? Do you trust that service provider? Think twice before using services like Dropbox. You and your data are rarely, if ever, in any company's best interests.