Most of the times I ordered physical gifts, it worked great. But... Myself, and two other friends I've talked to have all had the experience of ordering a Facebook gift, and no order was placed with the supplier, or it took days for the supplier to receive the order. Of course, there's no number at Facebook to call.
It took me 3 days to get a response from Facebook through their help system.
Meanwhile, Facebook had already told my grandmother flowers were on the way. They even provided a tracking number that did not exist.
I wonder how much the lack of customer support played a role in the 20% physical goods number. IMHO physical gifts was a poorly executed feature.