We did the Mount Cabot via the York Pond Trail and back - not the loop via the Lost Pond Trail. We had planned to do the loop, but the trail blazing was very poor and in bad weather it was just too much to take on.
Mount Cabot itself is very uninteresting - had it been 3,999 feet, I dont think it would get any visitors - In hindsight, I am very disappointed that we missed the Horn and its views since this part of NH is very isolated and wild.
The first mile is fine, but the next 2 miles are along the side (right bank) of a gently sloping trail which in deep snow is very hard - more so on the return. After that you intersect the Kilkenny trail and head straight up to Mt Cabot, which is a fine steady slog uphill. The top is in a small forest, where the only indication you are at the top is a small sign that says Mount Cabot 4,180 feet. Down is very quick until you hit the 2 mile trail that makes you want to lie down against the side and wait till spring. Needless to say, I did not do that, but was very glad to see my car after a 9.5 mile roundtrip that took 6 hours. The drive along York Pond Road was pretty tough too - a sheet of ice for the whole 5 miles or so.
Overall, I enjoyed the challenge, but would have preferred to do the loop. Unfortunately the trail blazing is very poor - saving paint? - more of a problem in the winter than the summer I imagine. Good luck!