I used to buy a coffee from time to time with bitcoin.
But I can't use bitcoin buying a coffee now, because the fee is so high, if I keep 0.0001 fee like before, it would take days for the transaction to get confirmed, I've got a transaction which took 11 days to get the 1st confirmation last month.
It's not cost-effective any more to buy (I mean both online and buying face to face) thing via bitcoin. And this is why I quit buy coffee with bitcoin.
Thats the part of bitcoin needed to be change and improve. We mine bitcoins to provide our needs so therefore we should get our earnings as fast as it can. Transaction fee getting bigger as fast as the growing value of bitcoin.