The white ceiling reflecting back is definitely going to decrease your image quality, but you may still find it acceptable depending on how critical you are. If you don't want to paint the ceiling black or other dark flat color, consider getting triple black velvet and tacking or stapling it up on the ceiling above the screen, and perhaps a panel on each side of your screen also, for a nice improvement in black levels and contrast. The velvet comes in rolls 44" wide and is less reflective than even the darkest paints, and is pretty easy to take down if you move compared to repainting.
I've had good results with the Elite Screens CineWhite and even more so with the excellent Silver Ticket white screens on Amazon, they are great value for the dollar.
POWER: Emotiva A-300, Denon AVR-X3300W
SOURCE: Oppo BDP-103D multi-region
SPEAKERS: Chane A5.4, A1.4, Rythmik L22 x 4 (dual FV18 on order!)
DISPLAY: Sony 45ES, 175" Silver Ticket screen