Initial Impression: Moat? Who needs a moat, I've got a mountain! That was followed by me firmly trying to place myself in such a sweeping castle and what it would be like to see it and know it was real or live there.
Perception Line: I start in the middle of the picture, the main cluster of buildings and then follow the bridge down to the gateway. After that my eyes sweep right to the side structures then right over everything to make sure I didn't miss anything.
Vision: This is a very visually appealing and distinct. I can tell it was imagined and implemented. Mostly it's completely believable except for some distractions in the land formations and towers.
Originality: Castles are hardly a new thing, they're rather old, and they've been imagined in every scenario possible. That being said I think this is a unique enough implementation of your vision that it is an original work. The way the castles almost grow out of the mountain side is interesting almost as if they might stretch down INTO the mountains.
Technique: As mentioned in vision some of the towers have tilts that don't sync up. If you look at the 3 further towers in the center you can see that all have the same angle. However if you move down to the stout tower which connects to the bridge it almost tilts towards the audience, unlike the back towers. The left tower on its own also tilts away from the others as if it's crooked. The same issue can be seen on the right towers.
Impact: I feel like this is memorable and I may even discuss it with other artists going. Yeah this one time I saw this picture, you should check it out. I also feel as if the fact it was a practice run and not a truly artistic expression shows in the subtle details like the tower, lighting, and such. I hope it inspires you to continue working though. It's certainly an attention holding piece, even if it isn't "captivating" yet!
I've been working on perspective for a while. I think getting that down better would help with the plastic look. I used to be happy if I got a result that looked like something I might need to re-think texturing a bit, too. I have a library of textures I made from taking snapshots, but I think I may need to pay more attention to the lighting in the textures themselves.