I think it would be nice to return a bool, rather than an error. It really is just a binary condition and this pattern fits nicely with accessing values in maps. That said, I haven't really found a need for a .Get method in my own code, and will probably just stick with encoding/json for the time being.

It looks like .Get uses the null pattern (ie, returns a Jason struct with data = `nil` if nothing is found). Your way is more idiomatic, but it looks like his point with this library is to access the data conveniently in exchange for type-safety. `exists()` can verify something was found if needed.