Yep its genuine Canon... its well designed in theory but something about it feels a little cheap in my hands.
There is a thin drop down plastic flap at the back where the 2xBP511/6xAA'a go... If you had some sort of accident whilst the flap was open it'd snap off.
Not sure what it is exactly, I just ebayed my bg-e3 and I'm certain the quality was better... it wasn't as fiddly putting the battery section back in though if anything I'd say it was heavier. I guess its possible Canon might have tried to make this grip quite light and in doing so have compromised quality a tad.
That said I'm still keeping it cos I need it... just slightly disappointed in its build quality,