Well a red and ND filter, certainly slowed the shutter down to give a nice effect.
I would think about burning in the light part of the trunk on the tree in the LH foreground as well as the light thing between the tree trunks on the RH side as well.
Not too much though, retaining some lighter tones but ensuring that your castle in the background is the lightest part of the picture would I think add more oomph to the picture.
I agree with the castle staying the lightest part...but I'd still try to bring out some more detail on the castle walls. Maybe the actual print shows more detail. Nice image, nice framing.
Nice framing. You obviously wanted the blur judging by the filters you stacked on, and I think it works. It needs straightening though, and you should consider the cropping options, bit off the top and bottom maybe?
Ithink the blurring of the bottom branches and leaves tends to confuse this section with the castle's background. My eye keeps jumping back and forth. Probably not a problem in colour but it wouldn't have the same impact in colour. I'd have gone for sharpness throughout. I don't think it would have prevented the castle being the main object