Travis of Wandering Mojave was quite knowledgeable about the flora and fauna, and he knows the park quite well. He took me on a multiple-hours, almost completely off-trail hike including some rock scrambling which was quite enjoyable.
However, I found him to be unprofessional. He picked me up at Autocamp Joshua Tree about 20 minutes late (5:20am instead of 5am) with no explanation other than saying hello to his wife in the morning after she was on a trip, and not setting his alarm early enough. Furthermore, his car smelled like smoke, and he rolled his own tobacco about 8 times over the course of the day. If anyone does not like the smell of cigarettes, do not go on an adventure with Travis. Lastly, our plans changed when my partner needed to work the second day we were in Joshua Tree, so Travis agreed to refund us for the second day which we had prepaid. However, it took him an entire TEN days to process this refund, AND he refunded me less than the agreed-upon amount. I was disappointed in this and will not be recommending him to my friends.
If you can look past this sort of unprofessionalism, he is a fantastic hiker and quite knowledgeable. I'm sure there's no one like him who will take you on an all-day off-trail hike. Still, be sure not to rely on him for refunds or for showing up exactly on time.