Spectacular site well worth the visit. Go early in the day before the sun and heat builds and enjoy the climb up. Also an early climb can avoid the crowds.
You definitely do not require a guide, so avoid the people at the base willing to help you. They say 'the cost is included in the ticket price', but this is simply a hook, so don't get fooled.
It can be a slightly scary climb upwards the rock, sometimes straight up a metal circular staircase, but still rather safe. Often can get very windy, so hang on to your hats. Also, although there very large wasp nests on distant rock overhangs, the site is carefully monitored, so no real worry.
Once on top you can explore the ruins, as well as the marvelous views below. A great way of spending a couple of hours