When Gitorious first opened up, I jumped on it with open arms and pushed up quite a bit of stuff there. I migrated some of the larger group projects I worked on, such as InspIRCd there, contributed to others, and made my best to use the place, generally.
And after a while, I found myself increasingly getting frustrated with things. The UI was clunky in a lot of places, buggy in others (merge requests and the like in particular caused a lot of grief to me), and there was no real insight or visibility about the problems or work happening to fix any of that. So, I migrated my personal projects to Github, InspIRCd also moved to Github (once I noticed that it had been in a period of lull for quite a long time), and as far as I can tell, nobody really looked back.
I'm not sure what to make of any of this, if it's a case of complacency on the part of the people involved, or simply a "worst possible storm" of multiple factors, but I certainly can't say I'm surprised, one way or another.
The only thing that does surprise me, is that it took this long.