James Gurney is a legend. His works is an excellent choice to study. I'm not going to offer a critique though. I'm hoping you would critique this for yourself - but to me. (psss I do think you did a good job but don't let that go to your head) You're doing this for study, so what did you learn? You wanted a to try and get a full range of colors with your triad, Do you feel you accomplished that task? What could be done to make your painting look more like his? What areas do you feel confident in your ability? What is it about his work that you like and would help you develop your own style? Did you choose Gurney because he's a master or because of something in his style?