We had been planning to go to the Boundary Waters for a couple years now and had heard/read enough to know what to expect - and yet we were simply stunned by the sheer beauty of the area.
The waters are absolutely pristine, the views on each lake are spectacular and unique. Even though we went during "peak season", we didnt run across anyone for 2-3 days at a time on our route. Really appreciated the crowd control via the quota system, although it means that you might neeed to plan your trip several months in advance.
We rented a canoe from the Tuscarora Lodge and the couple running the lodge (Sue & Andy) were just great. Very warm and helpful, very knowledgeable about the area and could advise us on ideal routes to take.
If you haven't canoed before, learning to portage is HARD. Would definitely recommend choosing routes carefully and packing conservatively. Having gone on several backpacking trips before, we were already accustomed to ultralight travel, which we definitely appreciated as we carried the canoe through the portages. It's nothing to get dissuaded by - just a matter of knowing your capabilities and planning accordingly.
The drive up from Duluth to Grand Marais (border town of to the Boundary Waters), all the way along the shoreline of Lake Superior, is a trip in itself.
Overall, absolutely spectacular.