It annoys me that it reverses the standard (err, value) callback convention that everyone else uses.
An advantage of the standard is that you might have 0, or 2 or more value arguments to the callback. So you can return (err) or (err, value) or (err, value, optionalExtraValue) and it's fairly consistent.
An advantage of the standard is that you might have 0, or 2 or more value arguments to the callback. So you can return (err) or (err, value) or (err, value, optionalExtraValue) and it's fairly consistent.