We did a lot of grinning and giggling on the holiday. Both of us were a bit hyper at the scenery, not helped by the fact that for most of the holiday we were the only people on the lakes. The first two days weren't so sunny, and there were literally 6 or so other boats on the 3 or 4 lakes we passed through, all of them were small boats anchored over some rocks fishing at various points.
It was amazingly empty. The lakes are bloody enormous (check out the map to see) and to have it all to ourselves, and surrounded by the autumn leaves and colours all around us was amazing.
If you ever get the chance, go. Especially at this time of year. But prepare for the weather - last week was unseasonable warm and dry, this week has rain and thunderstorms all week. Going in the last week of September is perhaps your best bet to catch the weather; the first week of October if you are braver and want more of the autumn colours.
It does get cold, though. Breezy and very open on the lakes and cold in the mornings. By which I mean 20 degrees in the day, so not THAT cold, but the wind was a little biting at times.