How was your Explore Tour Leader?
Ksang (not sure if that's the correct spelling), our Bhutanese guide (and his associates) were wonderful. The perfect mix of local knowledge and English-speaking.
What tips would you give to someone else booking this tour?
Make sure your sleeping bag is up to the task. Bring thermal under layers. Don't be afraid of the food; it's delicious. Understand that some of the days will be very long. Bring trekking poles if you're at all worried about your knees/other joints on downhill sections (which can be very long).
Do you have anything else to add?
There are direct flights into Bhutan from Delhi. It might make more sense to fly straight in, saving a day 'wasted' in Kathmandu. The itinerary provided by Explore diverged from reality by some amount. I'm not sure anyone from Explore actually went on the trek, despite the changes that were sent out. Someone should do the tour, or speak to Yanphel Adventure Travel directly for a correct schedule of the days.