In addition to the full 22.5 stretch described here, there are opportunities to shorten the trip by using a number of possible take-outs and put-ins along the way. The Great Allegheny Passage bike trail parallels the latter half of this stretch, and there are opportunities to use the parking lots in Garrett and Rockwood as convenient shuttle spots (a bike shuttle between those locations is straightforward).
Overall, at lower levels (around 3 feet), there are intermittent small rapids at times. These rapids are largely washed out at higher levels. The last several miles are essentially flatwater, which can be tedious when there is a wind from the west and little current. At high levels (over 4 feet or so), there is a consistent current that helps to whisk boats downstream, though there is less whitewater to look forward to at those levels.