I was lucky enough to be in the area on a gorgeous day (mid-70's in the valley, mid-50's at the peak and totally sunny) so it was a perfect day to take this tour. I don't think that it would be very enjoyable if you'd get to the top and would be socked in a cloud. For me, though, the view was excellent. The drive takes you through all kinds of ecological zones from forest to alpine in only about 20 minutes, so that is pretty neat.
There are definitely some pretty scary points on the drive when you get to a couple curves that are so sharp that you can barely see the pavement 2-3 car-lengths ahead of you so, if you're scared of driving under those conditions, you should have someone else drive. Once you're on top, though, you should feel safe and should enjoy the view.
I had absolutely no problems with my car's performance or braking. I put it in the lowest gear as told by the instructions which you receive with your ticket and hardly had to use my brakes. The temperature gauge on the car never moved from its midpoint.
I found the park staff to be pretty unhelpful. I don't know if it is because they are State Park staff (as compared to National Park staff) but they just seemed to be counting the hours until their shift was over. They pretty much acted like they'd rather be reading a book or visiting with each other rather than helping the visitors, I thought. (In fact, 2 of the 3 of them WERE reading books or newspapers...)
I've been to Glacier National Park twice and have driven and hiked the Going-to-the-Sun road multiple times at each visit. It is an utterly tremendous experience. If it is a "10", I'd give Mt. Washington an "8". Glacier is jaw-dropping simply because you are SO high but the mountain tops are still thousands of feet above you. When you're on Mt. Washington, you're at the top so there is nothing else above you to make your jaw drop. Still, if you can go when you can see to the horizon, you'll feel that you got your money's worth.



