I'm left wondering why the switch was made in the first place. I spend about half my time coding in Go and love the language, but if I wasn't looking for easier concurrency or a speed boost, I wouldn't re-write an existing code base in Go. It's a lot of work to do just to revert a short time later.
The majority of comments are fair, although I'd disagree with it being C2.0 and err != nil getting old - I much prefer it to exceptions.