Along with Shaky Flakes, Greasy but Groovy was a milestone in its day. The crux sections are crowded into the third and fourth pitches. The upper pitches are reminiscent of Tulomne routes -- run out 5.9!
I did this route in the early 1990s with Paul Horak, one of the best face climbers I have ever shared a rope with. Although the guidebooks give this route an R/X rating, I don't recall any anxious moments. Obviously, this is not a route for the faint hearted, but if you are confident on 5.11 face -- as were the first ascenders -- then the you can run up the run outs.
Finding the base can be a challenge. The key is to locate the easy ramp of the first pitch of Reefer Madness, then move down and right until you locate a line of bolts.
Some thin gear to supplement the quick draws is a good idea.