I don't know what it is, but I could never get into GitHub. Something about the general style and ctmounimy of the site always seemed foreign and a bit what's the word hipster. Couldn't exactly tell you why, just a feeling I got when I went there. Not somewhere I really wanted to be. I looked at BitBucket way back when and it was pretty much a GitHub clone. We ended up running our own private git server for awhile but then BitBucket re-did their site and holy moly, I love it! We've been on BB for months now and loving every minute, it's a fantastic service!