the nebulae is looking too good for the obvious fake stars. I don't like how you used the same star brush or shape repeatedly without ever thinking of rotating them. If you take advice i would say remove the fake twinkling stars, coz the nebulae looks almost real. instead put a small round planet. really small like about 1/10th or the picture size. it will greatly increase the depth of the image. Also if you are so bent on to keep the stars, atleast get rid of the big twinkling one's they are really spoiling the tone and mood of the piece.