Imo it wasn't that bad, but maybe that was just because code-centric sites like github didn't exist yet. It tried to provide you with a simple landing page for your open source project that can offer you a download button, centered around releasing compiled, versioned software. Their offering of a VCS (svn and CVS IIRC) was more of an added bonus. But once github was there you started wondering how sourceforge ever seemed good.
It did suck balls, but we were grateful to have it in a time where it was possibly the best option.