godep is definitely cool. But it's a bit sad that it has to be an add-on. Don't get me wrong -- it's a great thing that go gives us a good build system, a good test system, a good dependency system, etc. But if we end up using another build system, another test system, another dependency system, because the stock ones aren't powerful enough, it kind of ruins it :-)
Regarding private repos: IMHO it's much simpler to go to your $GOPATH/src/github.com/blahblah and `git clone git@github.com:blahblah/repo`. But if you know a difference between both approaches I would be happy to hear it!