Pros:
Holes #1-8 and 21 are well maintained, and therefore fun to play. As many have stated before, lots of people play those 9 holes twice to make up an 18 hole round. Why? See cons. It's fun playing disc golf next to a light rail line with a picturesque view of downtown Denver. Central location makes it more convenient when trying to coordinate games with groups from all over the metro area.
Cons:
Holes #9-20. A few of them have real potential, but overall this part of the course is a forgotten wasteland with overgrown weeds, graffiti, trash, vandalized and/or missing baskets, and so on. It's like the you walk into another neighborhood when you pass hole #8, one with much bigger concerns than maintaining a disc golf course in a drainage ditch. Many holes play on or near the bike path with blind spots, the chance of hitting a biker is always there. Bugs and snakes in the overgrown weeds, watch your step!
Other Thoughts:
Always crowded, get there early or be prepared to play a slow game. Try to avoid shooting your disc under the high tension power lines, it makes the hair on your arms stand up. Be careful crossing the creek on hole #9, the rocks get very slick. UPDATE: My playing partner and I both slipped and fell into the water trying to cross the creek on hole #9 today, it is currently unsafe to cross there, try walking around to the crossing by tee #20.