This WHS is already well reviewed by the first three reviewers and my visit was quite similar to that of Carlo and Nan. I will try to provide complementary information from my visit.

Like Carlo, me and my friend only visited the archeological zone of Yagul, and we were about the only visitors there. We started with La Fortaleza and enjoyed the nice view over the ruins, the surrounding mountains and agricultural fields around. You can see the little tableland-ish mountain where most caves are located. We then visited the ruins themselves. Many sings are within the site with plenty of information and make visiting by yourself quite easy. You can get into some old tombs, which is quite cool. El palacio de los seis patios and el juego de pelota remain the most impressive constructions there.

Getting there was not as straight forward and easy as stated by Nan in his review. Our plan for that day was to visit most sites in the Central Valley from Oaxaca, starting with El Tule and then moving to Yagul, Mitla and maybe Hierve el Agua. When we arrived where we've been told to take the collectivo for El Tule, most streets were closed and policemen where everywhere. We've heard that "pacific" protest happened the day before and that people died. So they were trying to control the traffic as much as possible and avoid other events. With the help of other tourists and policemen, we finally found the only street where cars, buses and collectivos were passing. But they were all full. We finally found a bus to the city of Yagul and from there took an overpriced cab to the ruins. Walking to the main road and finding a cab to Mitla was much more easy. I don't know either why Lonely Planet have a warning for this road. From there we spotted the rock art on the cliff (picture). The rest of the day went more smoothly with Mitla (way better than I expected!) and Hierve el Agua (really cool as well). We did El Tule on another day as it is really close to Oaxaca. I recommend visiting all these sites if you can manage that long day of uncomfortable buses and shared cabs.

I really share Carlo's feeling about having a great time at a minor site. The ruins are interesting, the landscape is beautiful, we were almost alone, the weather was perfect. Yagul is a nice site among other prehispanic WHS of Mexico.