As a long time user and occasional contributor to open source projects it was a jarring 'back to the future' moment to have to evaluate some software hosted on SourceForge as I haven't looked at it for at least 5 years and use GitHub regularly.
So it was pretty horrific to see a site littered with low-grade advertising and the greasy tricks of the internet marketing brigade around the site... the user experience horrible making me wonder why people bother with it.
The dev. outage came after that unpleasant reminder of how bad the internet of the 1990's used to be.
To heap injury on insult, the outage has created a significant blocker in a project I'm doing for a client where I am evaluating a number of open source offerings. The source has been unavailable now for over a week.
To those supporting Sourceforge I would say there is one massive reason why GitHub has a better future... I pay a regular monthly subscription that is entirely reasonably priced for the service offered. As a result, GitHub are motivated to support their customers and there is a sustainable business model that means I don't have to look through a UX cluttered with dreadful crap. Now that is worth paying for alone... even if outages still occur, though they are planned and last minutes instead of weeks.