Pros:
Willmore Park Is located essentially on the City/County border in South St. Louis. It's actually the youngest City park (established in the late 40's) and has a suburban park feel. The disc golf course is retrofit into the multi-use park and takes advantage of the rolling elevation to provide a nice variety of shots. All of the shots are park-style with a variety of trees in the way to complicate your path to the pin. The course has good concrete tees, good signs, multiple pin placements and Gateway Titan baskets. Most of the shots are pretty straightforward. Hole 11 in the long is over 900' and your approach has O.B. walking paths on either side and long of the pin, and hole 14 has a dramatic dropoff pin placement for some memorable shots. The course is on the longer side with some room to air it out, which makes it attractive to Advanced-level players. It sets up decently for lower skilled players because there aren't a lot of spots with a high danger of losing a disc and it's not a punishing design or one that forces you to use a variety of shots. All-in-all, it's a solid disc golf course.
Cons:
Willmore suffers from the dreaded "McCormack flow" problem which plagues so many St. Louis courses that the locals don't even notice it anymore. You can easily get lost at 3 to 4, 5 to 6, 13 to 14, 14 to 15 and 17 to 18 as there is long, golfless walks at all of these spots and inadequate (or nonexistent) signage to help get you from one hole to the next. If there was signage to help direct you, I'd chalk it up to the limitations of designing with a "good shots first, flow second" approach in a multi-use park and not ding the rating for the course at all. But there is no signage. Adding to the frustration is that in some of these long walk situations, there seems to be room for some golf holes. Overall the flow is so bad that I'd say it's impossible to play this course the first time without a map or guide as there is no way you would find hole 6. The hole 5/6 transition beat out the hole 9/10 transition at West City Park as my personal "most impossible to navigate without a map" hole transition.
There is in some cases a little concrete circle next to the basket with an arrow to direct you to the next tee. Oddly, I've never noticed one at 3,6,13,or 17, which are holes that really need directional signage.
The grass grows so long here that the locals actually take pictures when the mowers are out and post them to social media. In the spring and summer months the mowing schedule can't keep up with the grass, which makes just finding your disc in the fairway a challenge.
The course is a park-style design which doesn't really force you to do much. You can pretty much throw the same shot over and over here and get away with it. It's a plus when talking about beginner friendly, but a con when you talk about the challenge presented by the course design.
The park is really busy on the weekends, and there are walking paths close to a lot of the holes. You really have to be aware of the other users in the park. On my last trip I hit a woman with my putt on #2, there was a painted white line running down the fairway that I didn't pay much attention to. It turned out to be a cross-county path and it ran right by #2's basket. I never heard her approaching and she popped into my line of vision right after I released the putt. The disc hit her in the arm as she ran by.
The neighborhood to me seems safe, but cars get broken into here a lot. The "river" Des Peres runs right by the park; it's a glorified drainage ditch that can smell bad and can have a healthy mosquito population, between it and the long grass some bug spray can make the difference between a fun round and a really long day.
Other Thoughts:
Back in the 90's when I lived in St. Louis all of the courses were in St. Louis County. There was a desire to have courses in St. Charles County, the Illinois side and in the City of St. Louis. After Quail Ridge and Woodland were installed in '02/'03, the City was the last "want" on that list. It took another decade, but Willmore is finally the "City" course players had been asking for. It's a very popular local destination for players despite (in my opinion) there being several better courses in the area.
The park itself was donated by the developer of the St. Louis Hills neighborhood as at the time the land was floodplain for the River Des Peres. A lot has changed over the years, but the park can still hold some water in the right conditions. It's really not enough of an issue to be considered a con, though.
Willmore is a good course, so if you know your way around it's a good option for a round. It doesn't strike me as anything special, but it's a good solid course that makes for a fun round. Probably the decider for a lot of people is that some of the holes have really healthy distances to them. It kinda replaces Creve Coeur as a St. Louis course with some long holes and the space to air some shots out, except it adds in elevation changes that Creve Coeur never had. If you like to air stuff out, Willmore is a really good option. If you lean to the more technical golf, there are better options.