Pros:
This is easily one of the most unique, fun, cool, exciting courses I've ever played. Situated just below a ridge near the top course, down under has a completely different feel to it. It's like a magical walk through the woods, just with baskets and tee pads.
For being so heavily wooded, this course did an excellent job never getting boring and mixing things up. Lots of elevation change and a good amount of left-right vs right-left shots keep things balanced and fun, in spite of the huge amount of trees.
Stunning views. In spite of the road noise from nearby Mission Road and I-35, you get treated to a lot of great views, including a gorgeous vista of downtown from the first part of the course. Overall, it felt extremely woodsy and was a very peaceful place to play.
The elevation here is used perfectly! Holes and tee pads frequently sit next to steep dropoffs (as with the top course), and there's lots of drops all over the course, making you really think before you shoot.
I can't really call the lack of signage, worn tee pads, and the like a "pro", but in a way, it almost adds to the ambience. The abandoned cinder block building between 12-13, general lack of anything but nature and DG, and various beaten paths just kind of "click" together for a gorgeous experience.
There are a good amount of "benches" and trash cans throughout, even if the benches are just old wooden spools or tree stumps. It's a place to sit and put your bag up off the ground and that's all I care about.
Baskets are bright orange and easy to spot in the woods. We played just after most of the leaves had fallen; this might be different in Summer, but we rarely (if ever) had to shoot blind on this course.
Most of the baskets are in good shape. Not the grippiest I've ever played, but very functional and the color really helps with navigation. Trash cans abount at most tee pads as well.
The bluffs shield you nicely from the wind; we played on a day with 40mph wind gusts and it was barely a factor in our play, with the trees and hills blocking for us. I can imagine the shade would be nice in Summer as well.
Trash was well managed when we were there; cans were mostly empty and it looked like people were using them and not the ground, which was nice.
It's neat to feel so isolated even in the middle of the city. The lack of signs, concrete tee pads, and wood benches almost helps to add to the atmosphere and doesn't affect the gameplay too adversely. However, this also means...
Cons:
...the big downfall on this course is navigation. It definitely has a rougher feel than its up-top cousin, which is really neat and unique, but navigation can be problematic. We played alongside many other groups which helped, but on many holes, especially the woods between 12-18, it's not obvious where you're going and it's easy to get lost. (FYI, keep walking past 12's basket until you see the old stone building on the right. 15 plays back up the hole you climb down to get to the tee pad. Hang a left to get to 16. 17 is a left dogleg shot, and 18, shoot from the teepad on the right with the memorial by it).
Again, tee pads are mostly dirt which makes it harder to get footing. There are a few signs giving the hole numbers, but not many, so pay attention. We found watching for trash cans to be the best strategy.
Wear good shoes! The footing out here can be treacherous. It was after most of the leaves had fallen, and I can imagine it's a muddy mess after any kind of rain too.
Lost disc opportunities everywhere - your discs WILL roll if they take any kind of bounce and with so many dropoffs, you really have to watch them.
This course is crowded, so prepare to see lots of friendly faces. We generally met up with super nice folks, but be prepared for some crowds.
Other Thoughts:
Rosedale is very centrally located in the metro; take I-35 and get off on Mission Road, head south, and hang a right. To get to the down under course, go to the pin for hole 1 up top and look to the right; you'll see a little staircase that'll take you to the first hole.
This course is so unique and different that I feel it deserves its 4.5 rating. I've never seen a course use the nature available to it in a way that's so perfect and really adds to the experience. The technical aspects of this course are fun, but it's the way it flows with the nature that makes it so unique and cool. It feels like a DG course perfectly slid into a part of the park they couldn't use for anything else, and that unique experience makes it worthwhile.
Keep in mind that if you're a huge fan of creature comforts and the like, you won't like this course as well as I did. BE PREPARED to walk on some rocks, climb some hills, and maybe scramble down steep ravines to get discs. It's very rough around the edges and the tee pads, navigation, signage, and footing isn't what you'll find up top or at many area courses. But, if you're here to play disc golf and don't care about the creature comforts, I think the 4.5 rating is worthwhile. Happy discing down under!