A lot of people (myself included) do not have problems with FaceID if they hold the phone pointed towards their face, from a foot to an arms length away from their face. Mine will work 99% of the time like that. The issue most of us have, is when the phone is in other situations. If it is not pointed towards your phone.
For example. You are sitting at an office desk with the phone on a wireless charger. Before, with TouchID, one could simply leave the phone flat on the table, use the TouchID to view everything on their screen. This is impossible with FaceID, one would have to lean over the table, to get their face in view of the FaceID sensor.
Anther example, laying in bed/couch. If you have the phone off angle you have to move the phone and your face to get it into view of the sensor.
Last example (there are more than 3 real world examples), if you have a car mount, that points towards the back fo the car/truck/SUV without it being angled towards you. You now have to remove the phone from the mount to unlock the phone. Before anyone goes crazy, use the situation where you pull over, are parked, and need to enter a GPS address in Apple Maps.
The iPhone X has a brilliant OLED display, one of the major benefits to an OLED display is viewing angle. By not having as wide a FaceID sensor angle as the effective angle of the screen, it becomes an adjustment. I personally have no doubt that the viewing angle will improve either via Software or Hardware. In the end, there will be less and less situations where FaceID requires a certain set of parameters. It just would have been nice, if when we bought a $1K+ phone, we had the option of using a TouchID in addition, to the new generation 1 FaceID tech.