Excellent post on Quora from the founder of Syncplicity, a Dropbox competitor.
If you’re starting a new company, the best thing you can do is keep your feature set small and focused. Do one thing as best as you possibly can. Your users will beg and beg for more functionality. They will tell you their problems and ask you to fix it. […] Until you have a lot of resources, stay focused on your core competency.