WOW! Is all I kept saying to myself for the first few hours. This trail is amazing! I LOVE IT!
I went on a hot day, 35C, in January 2021. Not sure when the last bush fire was, but the trail was bursting with green and life. I saw an echidna (who didn't seem to care at all about my presence), and emu, loads of kangaroos, lots of birds. The landscape forever changed, from sparsely forested, to tight, tight, tight, to steep to flat. I hung out with a 300 year old tree, not a bad sort, taught me a lot about my silly behaviour and rushing around, then I rushed off.
The only reason I don't give this a 5 star is it's only the East side, the steep foot path bit around King Jarrah, that I thought was extraordinary. The rest of it is still AMAZING but the trail is on a vehicle road, so is wide and not a hiking specific trail. It just feel different. The bush was still amazing, the views were still great, but it feels so much nicer being on a tiny winding trail through the bush than a wide cleared space. Again, honestly, even that part is great, the forrest here is such a uniquely WA experience.
Enjoy. Oh and when you're on the wide trail, listen out for a running creek and see if you can get to it through the bush. It's only about 30cm deep in the summer but a great spot for a swim and cool off. Also, if heading in the summer I would recommend the mornings, wrapping up in the East bit (heading clockwise from Nanga) as that way you'll be in the cool of the forrest by the time you're done.
Also, it took me about 6 hours but I did it really slowly for my health and fitness. I'm 35 and strong as an ox, but I had quite a few long sits along the way.
Say hi to the King.