I just received this yesterday for use as an aid in night-sky photography. I was able to connect to my 5D3 camera, remote focus, zoom and live view within a few minutes of receipt. Connection is made to the CamRanger via an ad-hoc network, the iPad app is trivial to use and LiveView performance is quite good - I would estimate about a 100-200 mS lag, which does not substantially impede manual focusing.
I ordered the extra battery, but I wouldn't recommend doing so to others. Removal of the plastic battery compartment door is clumsy and I suspect that repeated removals will break the retaining tangs in short order.
Overall, I am content with the purchase.