I went on a 16 mile trip over two days. I started off 75th street into the eastern branch (by Zero gravity and 75/53). I continued on to Riverside park in Plainfield, getting out just before Rt. 59. I did 10 miles on day 1, and 6 on day 2. The river was flowing nicely, after some decent rains earlier in the week. I spend about 6 hours in the water to do the 10 mile leg on day 1, and that was with frequent bathroom, food, and portage breaks. Day 2 was 6 miles in about 3 hours. Although I took less breaks, I didn't paddle as hard.
Overall, it was a great trip. The eastern bit of the dupage river is quite shallow, but perfect for kayaking. I scrapped up plenty of times, but was able to slide over the mud and gravel fairly easily. Then again, it was early season, and the water level was higher than normal. Once you hit the east west merge around 95th street, the water level deepens.
While you are passing through plenty of subdivisions and roads, it's a nice slice of nature in the backyard. It's not nearly remote as the lower fox or Illinois rivers, but it was much better than I would have guessed. There are thick trees covering you most of the time, so it's almost like a tunnel of nature, and gives you natural separation.
If you take the eastern branch around Whalon lake, there are some nasty portages because of BEAVER DAM blockage! There is another riverside park west of Whalon lake, so I'd recommend that as a starting point for this reason. While these aren't long portages, it's through thick grass covering fallen branches, and most of the banks are steep. I probably lost an hour trying to navigate, move, and rest after these tough portages. These beaver blocks did not show up in my satellite image research.
There are not many islands until after passing Naperville Plainfield road. It's also a lot more remote after the merger. Just plan of camping past that point, should you decide you want to go.
This river is not built for canoes. The water was so shallow at points, it would have been tough in a bigger boat. My kayak could slide over these shallower parts, but the tall sided canoe would have been tough to move. South of the merger it's better, but I don't know if I could recommend it still.
There are lots of eddies and lines. If you are paying attention and hit most of these eddies, you can start cruising with minimal paddling.