Just back from an Ethiopian tour (Feb 2016) and really enjoyed the context provided by this book!
A couple of updates/plugs from my trip:
VISA ON ARRIVAL
It was difficult to find up-to-date information on the requirements for getting a visa at Bole airport. Note that you do NOT need passport photos. They have modern webcams that take your picture there on the spot. Also, to clear up one point I found confusing, you can pay the fee in a variety of major currencies, not just US dollars. I paid 50 euros and even got change in euros! There is a foreign exchange office pre-visa if you get really stuck.
As there are sooo many guide and tour options for the Simien mountains, I wanted to put in a plug for our super-organized, super friendly local guide Gismu Syum with Ethiopia Trek (http://www.ethiopiatrek.com/). He’s incredibly responsive over e-mail (rare indeed!) and a very good choice for budget conscious travelers, particularly those organizing their Ethiopia tour independently and just needing a guide for the Simiens and/or Gondar. Personally, I cannot even imagine trying to go through all the red tape to organize a trip myself in the Simiens to save a few bucks when you could go with someone who knows the ropes and won’t charge too much for bringing you through it, like Gismu!
I would also note that Chennek camp was a highlight and I strongly recommend doing at least a three-night trek in order to get at least that far.
Note that the entire village of Geech has agreed to a government proposal to relocate and will begin moving out of the park boundaries in March 2016. While this will definitely have a positive impact on the wildlife in the region by restoring the heavily farmed land, it does remove one of the few reliable village stops in the early stages of the Simiens route.