For the first few wears, it is uncomfortable and gives you blisters. But somehow after a period, it magically becomes more comfortable; this is called the break in period.
A few tips:
Put on thick socks on your feet.
Blast one of the shoes all over with a hair dryer for around a minute, until it’s warm and soft.
Put the shoe on your foot.
Repeat with the other shoe.
Walk around your house at least until the shoes have cooled - the longer you can keep them on the better.
If you have time, ideally do this a couple of times.