I'm not sure that letterbox works for me here as it makes all the details look so far away . . I think I would rather have had a squarer format so I could have luxuriated in the rich autumnal colours more.
The colors here are beautiful, we didnt get much in the way of fall colors this year. I can't help thinking that I wish you had cropped the right hand side so that the green tree isnt in the shot which would have enabled you to make the rest of the photo larger (zoomed in so to speak) by taking advantage of the file size we are allowed which would have put those beautiful colors more "in your face". Another option would have been to crop the dark part off of the left which is a bit distracting, while still leaving the mansion/castle in the frame. There is a not a lot going on on the left side but I realise that it would make the building really close to the edge of the frame.
JMHO of course and nonetheless a beautiful bright picture, good luck. 6