I like it, glad you mentioned it was intended to be inspired by Minas Tirith, as that was the first thing I thought of when I saw it. Unlike that embattled city of guard however, yours has a peacefulness to it. As if Gondor had never had a Mordor to contend with.
The mountains are well done and realistic. Not sure about the play of light coming through the clouds. The light is so intense near the flying ship it makes one assume the sun is in that area of the sky. But then there is the light coming through the clouds off to the left. Given the slant of that light, it makes me think there are two different sources. It's a fantasy picture, so no reason there can't be two suns, but just something to keep in mind. The ship is really the one element I didn't like, to be honest I wasn't sure what it was. It's a little overwhelmed in the light, and I don't think it adds anything to the composition as a whole.
I like the mix of colors. Given it's a city set against a mountain range- your going to have a lot of grey/white look. But you brought life to it with the greens and I particularly like the dark blue area on the nearest mountainside. And the purple'ish mountainside area rising up behind the city.
Hope my comments were helpful in some small way. I must say, overall great job.
i´m not an expert,but maybe you can put some textures,via overlay layer(you can manipulte detail level,with level option)like rocks,folliage,or texture wall for that nice castle. Soorry for my bad english. i´hope can help you a litle anyway the work are amazing