Pros:
Every hole seems like it's set in it's own little world, even though you can see other holes nearby
Logs have been flattened into benches on pretty much any hole, and you'll need them!
It's not a brutal, torture track, but it also doesn't give up shots easily
So many fun downhill throws! Even the sharply uphill holes are fun.
Odds of losing a disc are very low. There are a couple of places where you might lose sight of the disc going over a hill, but the woods are entirely rocks and grass so you should eventually find the thing even if it's way off line.
The odds of you getting lost are low. Sure it's a big course, but it's easy to see where to go.
Cons:
The rocks! Some of the holes in the woods are on a steep hillside that is mostly rocks. Some are loose and really you shouldn't step on any of them if you can help it.
The course has a Gold tee and a Silver Tee (shorter) but if you are playing the Silver tee, you have to walk by the Gold tee anyway. There are a couple of holes where the Silver tee gives you a somewhat different look at the basket, but there's really no reason to not play the Gold tees. You're going to score about the same over/under par anyway.
When they say the grass is long in May, they mean it's thigh high and you're going to not see your disc in it unless you're within a few feet. Holes 16 and 18 are deeply satisfying long downhill tee shots, but in May you're throwing it into this thigh-high grass. You must get a good line on where your disc lands. 17 is perhaps the best uphill hole I've ever played, and you are in the same grassy field, but for whatever reason it was easier to find the disc
It's nice to have 2 tee pads, but they could really use two baskets too. They have plenty of room, and they could create 2 more layouts, one even shorter than the current Silver card, and one longer Gold card. They could position the baskets to cut down on some of the walks if you're playing the Silver tees to the short baskets.
The stretch from 6-9 isn't as exciting as the rest of the course, but they aren't exactly bad holes. They're good parkland style holes. 8 would be the best hole on pretty much any typical park style course in the area.
Other Thoughts:
It's like a fantasy world for disc golf. You're in a park, but there are no pedestrians to avoid, unless for whatever reason they're wandering through the woods. The holes the woods have some pretty tight lines, but you can miss your line by miles and still find your disc. Oh, you won't have much of a shot, but you can at least find it and advance it.
Usually uphill holes are painful and boring slogs, but this place has found a way to make them exciting. 1, 3, 15 and 17 are all sharply uphill, yet strategic and fascinating too. And to reward you for your trouble, there are some fantastic downhill throws too. 16 and 18 are incredibly satisfying, as is the long approach shot down the rocky hillside on 14.
I'd probably avoid going here when it's really hot or in May. This place is no doubt a total blast on a nice calm 60 degree day in October.
If you're familiar with South Hills and Lenni Lenape in Lebanon, Muddy Run would be like the 9 best holes at each course combined into one, and then all of them stretched out 200 feet farther, with much wider playing corridors.
The fact this is a free course to play is almost hard to believe but here it is!
I debated between 4.5 and 5 discs because while there are 2 tees, Gold and Silver, the Silver layout just isn't as good as the Gold. If you can throw the disc 250 feet and relatively straight, the Gold course isn't going to be too hard for you and is way more fun. It is possible to par every hole and you'll have a few decent birdie looks. The Silver layout reduces the distances some, and lowers the par accordingly, but you still are walking the Gold layout and missing out on some really fun gold tee shots. For example, 16 and 18 gold tees both play from the top of a hill, and the silver tees don't. . Also, if you play Silver 14, which is a still a fun par 4, you are missing out on one of the great par 5s in disc golf.
The Gold layout is clearly 5 stars. The Silver is more of a 4.0. If they added another set of baskets to each hole and found a way to cut down a little on the long walks if you're playing a shorter layout, this would definitely be a Best of the Best course. Several other reviewers have said this is a 4.75 course, and I'd agree with that but I'm still giving it 5 discs. From the back tees it's a brilliant, thoughtful and fun course that is not overwhelming to the average recreational player.. Just because the forward tees are a bit weak doesn't mean I should downgrade the rating.
It's a wonderful place, worth the drive to the relatively remote location.