Why do gift cards even need a review?! It's essentially a little piece of Amazon software that "just works". The designs are pleasing and at their worst, inoffensive.
The inability to use Amazon Pay balance for buying a gift card is the only negative, and not a big deal once you know about it.
P.s. I topped up my Amazon Pay with around 2000 Rs each from 2 different cards and I was unable to use that money to buy a gift card. I don't know why such a restriction exists. This was around 6 months back so the situation might have changed.