I find that my sinuses often get severely dry on long-haul flights. I wouldn't call it pressure but it's really painful and worsens as we descend. A pharmacist at MUC sold my a saline nose spray that is all natural and cures the pain and dryness.

Sometimes some people are susceptible to sinus pressure if they may be sick or getting a sinus infection or have sinusitus. One flight a friend of mine was in excrutiating pain on descent and then it lasted for about two days after that. Everyone else was fine including me.....