Two other kayakers and I recently did two sections of the Middle River near Winterset, IA. On the first day we had planned to do from Middle River Forest County Park to Roseman Bridge, but ended up taking out early at Schlidberg instead. This was for two reasons - we got a late start at just before 4pm, and the river going was slow. This was due to a lot of downed trees in the water that required portage around, and the fact that this first section of the river was all mud/sand bottom and banks. Every portage was a mess, and one of our paddlers even sank up to his knee is the mud on the bank.
Still, the scenery was very nice, and the riffles and chutes were interesting but not dangerous - perfect for us with less experience. The put-in at Middle River Forest County Park was terrible - just a bank of mud with a good foot drop into the water. Take-out at Schildberg was a bit better, but still something of a challenge for us relative noobs.
The second day we started at Roseman and took out at Pammel State Park - this was a very nice trip. Beautiful scenery, and best of all - rock bed and banks at all the important parts! Every portage or shallow riffle that caused us to exit our boats was so much easier and less messy than the first section. The put-in and take-outs were also much nicer and easier to manage.
We had hoped to go all the way to Winterset County Park or even the Holliwell Bridge, but sadly didn't have time. We'll definitely do this again, but starting at Roseman and going to Holliwell.