3. Because of the slow approval time of the transactions, the crypto coins can't be used for buying things in physicals stores. Nobody will want to wait 5 min. for every customer to get the transaction approved. Imagine the size of the queues.
Physical stores don't have to wait for the confirmations, you are showing your face and shoplifting is risky/difficult even with zero confirmations.
Another problem: Transaction fees aren't really explained in the qt-client.
(Sure, you can find out about them in forums etc, but this will take some time)
