Pros:
This is an excellent course in one of America's finest city parks. There is a great deal to see and do in San Francisco, but if you love disc golf you will definitely enjoy a trip to Golden Gate Park for a round of 18, you can even throw in a trip to a museum or concert or other activity in the park. As usual, the atmosphere is relaxed and as always San Francisco seems to have a festive feeling to it, and this place is no exception.
One is first struck by how nicely the course has been laid out and prepared. Very nice concrete tee pads, wonderful signs at each tee (on angular cut round wood posts), and well-maintained fairways, steps, and paths (the paths are even lined with wood in many locations).
When Golden Gate park was established after the great earthquake of 1906, much of this land consisted of sand dunes that stretched all the way to the beach to the west. The area where the course is located contains many large trees (a mix of pines, redwoods, eucalyptus) which in turn provide a nice canopy over most fairways and make for very nice obstacles.
There are a front 9 and back 9. On the front 9 the hole lengths range from about 230 ft to maybe about 330 ft, the fairways are somewhat tight but not wicked, and you might think the course is too easy. But the back 9 seemed to be much more challenging (at least to me), with more obstacles and trees, much longer distances (over 400 ft for some placements), lots of up and down hill action, and risks galore.
My favorite was probably hole 10. In one of the pin placements the basket is on a large stump down in a ravine, and you tee off from high up the side of the ravine. There is a mandatory that makes you throw a big left-turning air shot downhill. A birdie on this hole would be very satisfying, since running at the basket instead of laying up can be hazardous.
Cons:
The course ground is a bit dusty, even when the air is moist and foggy. Bring a dust rag and dampen it occasionally with water to wipe off the discs. Follow a group of locals to be sure where the next tee pad is, or you might be a little lost on a couple transitions (9-10, 14-15, etc.).
Other Thoughts:
This portion of the park is very nice, and is used to host several large outdoor concert festivals throughout the year. Check the course web page before making a trip to be sure it isn't closed.
I don't live in San Francisco ($$$), and usually travel into the city on BART into the Union Square area (Powell station). It is really easy to get to the course from Union square by taking bus line 38 west on Geary until you get to 25th Ave. (about a 20 minute ride). Then just walk south downhill to the Park and you'll easily find the course to the right across Fulton.
There aren't many stores immediately nearby the course to pick up beverages, so you might want to grab some before you head into the neighborhood.
After a round, go west on Fulton until you get to the beach, turn right and head uphill and go to the Cliff House (a National Monument) for the greatest bar in all of the city.