Pros:
-Tunnel shots, narrow fairways, long baskets, short baskets.
-Dirt course, no grass holes; I prefer mountain courses.
-18 hole course, but has alternate 'A' and 'B' holes between holes 5 and 6, and 'C' and 'D' holes after hole 12. C and D are the only real open drives on the whole course. These are great for navigating around large groups; sometimes you skip them to pass the groups, sometimes you play them to create more of a gap between them. I think its a great idea, and effectively makes the course 22 holes.
-Wide variety of DG'ers. Old and young, and get this, some are even female!
-Concrete tee pads except on bonus holes.
-Lots of shade on most of the course.
-One of the best course websites I have encountered, with a detailed description of what each hole involves.
Cons:
-Poorly marked. No signs at any tee's, and fruthermore, many tee pads are now mis-numbered. A guide or map the first time around is almost essential, particularly after the first 5.
-While there are many nice locals, there is also a large chunk of people that treat the course as their own, and would probably like it if nobody else ever played there. Ever.
-Some blind holes can make for some 'fun' disc finding.
-Bonus hole 'A' is a very narrow tomahawk throw that is harshly punished if you mis-fire.
-Summer Camps can make the front 9 a patience challenge, hole #6 is removed in the summertime. I believe they replace it with bonus hole B for scoring purposes.
Other Thoughts:
Oak Grove plays in a heavily wooded park in an area that is largely DG exclusive. There are usually people walking dogs, riding horses, and using the other recreational facilities so always keep an eye out for others. They are all well aware of the course. Hole 6 is taken out in the summer time due to a youth camp that takes over the area.
The Front 9 play generally around a large athletic field along an oak covered hillside. At hole 5, you are introduced to the parks other personality, which is a more open, yet equally as challenging flood basin.
The back 9 mostly plays in a heavily wooded section of the park, with relatively close fairways, a pair of double mandy's, and some other tree and object related hazards.
Three of the back 9 holes (and when I say back 9, I am referring to the last 10 holes) play back down in the flood basin. These are two of the three only wide open shots on the course. In the wintertime, one plays across a lake. It's not the longest throw in the world but its easy to screw up.
Hole 9 has an alternate tee that largely eliminates any blind throwing that is encountered from the concrete tee. Simply follow the little trail just beyond it and you will see a rubber tee. Since I am not a fan of climbing around in bushes, we usually play this tee.
While navigation is a nightmare for first time visitors, I really like the course. Definitely more pleasant to play in the winter and spring, but what course in Southern California ISN'T more pleasant during those times? The park regularly sees a large crowd so I don't think they are in any hurry to add signs and help newcomers.
For historic purposes alone, this should be a stop on any disc golfers list. Do yourself a favor and print up a map from their website before you head out, bring plenty of patience, and keep your eyes out for random discs, as many fairways play incredibly close to each other.