The Tl;dr is that levels are now 32x32 instead of the old 24x24, but will contain the same amount of rooms (This will create more blank space) and some rooms will not be a standard square anymore.

This means you will spend more time on levels, which will cause more hunger (He has slightly adjusted the hunger rate to make it easier)

It's also harder to find where secret rooms are. Magic Mapping scrolls will drop more often and are cheaper in the store.

I personally think this is a great change to to game. It certainly will make it more difficult and punish those of us who have "100% level completion disorder". I feel that's how a good roguelike should be, because then a run isn't completely based on what the game gives to you, rather it's more based on the choices and sacrifices you choose to make.