Pros:
Hidden Valley makes a casual round and plays pretty fast with good tee pads, amenities, and simple navigation. The tee signs can be seen from miles away and while they don't have maps, the holes are simple enough it doesn't matter. It's pretty beginner friendly, with few tight lines and good upkeep.
There's some elevation on every hole that at least tries to keep things exciting. On some holes, it makes left-to-right or right-to-left lines a bit harder, and on hole 7, you can't see the basket from the tee because of the hills, and the distance makes it the hardest hole on the course.
There are two pin placements on nearly every hole. I'm not sure how often they get moved, but the fact that they exist shows that someone has cared for this course at some point. There are grey posts where the alternate placements are.
Hole 4, the only wooded hole, has several different lines and opportunity to be in trouble if you miss your line. You can throw over the trees on the right, or try to pick a gap through the trunks. Hole 5 ends near a treeline, so an errant shot can produce a short shot but with no line to the basket. On the open holes, wind can be a challenge.
Cons:
There are not many trees at all, other than hole 4. While it is good for beginners, it becomes boring when there's just nothing to work with. Even if a few more holes could play into or out of the woods, just slightly, there would be a lot more challenge available. I know there's an apartment complex and a road that must be avoided, but there's at least a little space for a fairway or two. If nothing else, there are some ace runs here.
The layout has a few issues. The baskets of holes 1 and 2 are really near each other, and there's no way to tell which is which. It also means the walk is long to get to hole 2's teepad. Several other walks are longer than they need to be as well. If the holes were amazing, it would be fine, but that's not the case here.
Safety can be a concern. The course tried to stay away from the rest of the park, but there are opportunities for errant shots to cause trouble. With wind being a factor here, this can certainly happen. On hole 9, the playground is nearby, and while it's a decent distance away, the playground is down a hill to the left, so a shot that's just a little too high could go there. If I wasn't confident in my overstable RHFH skills, I would have taken a much safer shot.
Other Thoughts:
The land on the eastern part of the park is much better suited for Disc Golf, and has less (if any) other park features. Hopefully a back nine can occupy this space someday. And when it does, hopefully a few of the issues with the existing holes can be cleaned up as well.
As with most courses in Kansas City more than a few years old, the baskets are these garbage Mach 3's. But being a casual nine-hole course, I don't care that much.
This is never going to be an amazing course, but it has the potential to be one of the better beginner friendly courses in the area. Considering the difficulty of some of the other courses nearby, this is a big plus. Other than that, there's not much to rave about here, but nothing too much to complain about either.