This is a friendly class II-III run with an easy shuttle that has a spattering of friendly surf waves, and a couple nice wave trains at medium flows. The creek flows through agricultural land, but is incised enough that it is not typically visible. The run can be extended by putting in a few miles upstream (44.994338009959556, -123.42063733950958) at a roadside pull out out, or by continuing downstream on the South Fork Yamhill into Sheridan. Do not put in at Mill Creek Park unless you are interested in the class V rapid just downstream. There is often wood present on the run, but don't be surprised if no portages are needed.
There is a painted gauge at the Hwy 22 bridge, 3.5 is a medium flow. Below 2 the run will probably feel low. There is no upper limit, but at 7 feet the eddies are small and the wood is a concern. It's probably too stressfull at 7 for paddlers who would normally enjoy this run. 2,000-4,000 cfs in the South Yamhill @ Willamina is probably a good medium range to shoot for if you don't already know the run (but that's not a hard-set rule).
The following video at about 3.5 covers most of the run just below the class V rapid mentioned above to just below the confluence with a swollen South Yamhill:
Mill Creek (Yamhill) SUP