If you are actively using the phone, the crease is invisible in all but the absolute harshest of lighting - anything close to a comfortable reading angle indoors or in some level of shade makes it a non-issue. You can basically tilt it maybe 10-15° in any direction before it becomes visible.The crease is really not noticeable – holds up phone and shows noticeable crease. Apart from that it does seem to be some pretty cool hardware and software.
But you don't have to lean it too far outside of that angle for it to show up - I'll see it when I turn the phone to show someone next to me a photo or whatever, and I'll see it if I have it resting flat on a desk behind my keyboard and mouse etc. It's not gross or even remotely deep or anything but it's there.
But then if I'm leaving it on my phone and want to glance at something I tend to have it closed and use it as a phone.