Dropbox is great and I use it all the time for personal use to share static files with friends like pictures, videos, or documents... however I will never use it for anything serious to do with my work because of two really big problems.

1 - Doesn't use static address' by default. With other services like Google Drive each file is given an ID and when that file is share is uses that ID to share it. This means that wherever I put that file, whoever I transfer it to, even if I change the title the URL to that file stays the same. Not true for dropbox. I don't know if there is an option for this but it's not worth the hassel to find out.

2 - Editing a document almost always causes a problem. With Google Docs or Microsoft One drive the docs that you collaborate on are updated in real time and are never in conflict with one another. The problem with a 3rd party solution like dropbox is that it can't update in realtime which means that if 2 people are working on separate computer there are 2 docs created. Then the other machines have to try to integrate the docs themselves. With 2-3 people this usually works alright but when 5 people are working simultaneously on the same doc someone's work usually goes missing.

Also for personal accounts 100GB = 99$ a year vs Google Drive 100GB = 24$ a year...

I have 23gb for free though so I don't complain ;)

I use many online storage services. While Dropbox is not my main one I use, it is reliable and easy to use. I mainly use it because several companies integrate automatically with Dropbox for automatic delivery of products, like eBooks. (e.g. O'Reilly, and Pragmatic Programmers). But, they charge a premium for extra storage so I just use the free service.

I use Dropbox both as a user and as a developer. Their products are awesome, fast, and super-great all around. The same go for their APIs — the Datastore API gives you real-time sync, for free, in a few minutes. I haven't found anyone to beat them on either side so far.