I had my first and only sinus surgery to date about 5 years ago. The reason my doctor recommended it was because of polyps, inflammation, and I literally had gallons of snot dripping out of my nose 24/7, regardless of the season or if I had a cold.
They basically go up through your nose with an endoscope, and depending what your exact problem is, will remove polyps and gunk. I know for me they also removed two bones from my sinuses to allow better drainage of all the snot, lol.
Many CF doctors will shy away from sinus surgery because often times once you have one it opens a can of worms and you will need them frequently. Honestly though, if you are in pain or your issues are really becoming bothersome, I'd say GO FOR IT! It's instant gratification, I could finally breathe through my nose. Good luck!!