I was very skeptical about the notches. But after a month of use, I find that I don't notice the missing space at all.
Most often, it really does feel like the entire screen is being used. It's almost an optical illusion.
My two minor issues with the X are: 1) the glass back makes it very slippery! (It slides off the arm rests on my couch no matter how well I place it.) 2) The protruding camera on the back is very noticable. I wish Apple would make a flat-backed phone again. When I set my phone on a flat surface, it shouldn't wobble.
Overall I was very skeptical of the X for a lot of reasons... but it's by far the best phone I've ever used. (And it better be at this price!)