Sorry for my late reply, I completely forgot about this thread.
It's now been six months since my little visit to Addis Ababa, but I figure perhaps I'd share my experience.
I arrived with Ethiopian Airlines from Dubai at 7.35am. The station manager at DXB issued hotel vouchers at check-in already, and I was instructed to visit the transfer desk upon arrival in ADD. The transfer desk experience was not the best. The staff had a really terrible attitude, where they essentially had the mindset of the customer always being wrong. I was refused my hotel stay, meal vouchers and transit visa as promised in DXB, and instead the lady behind the desk tried to sell me a dayroom for $100 in cash. My other option was to spend 18 hours in their dull lounge. No chance in hell.
Given the fact that my flight left DXB at 4.30am, and I only slept for about two hours on the flight, I wasn't in the best of moods. So after a lot of arguing and shouting, I finally managed to speak to a supervisor. The supervisor was very professional, and pointed out that since my voucher was already stamped and signed, I would be entitled to a transit hotel.
The agent who was now slightly ashamed after being proven wrong by both me and her supervisor, reluctantly gave me instructions to the hotel, along with a laminated slip of paper that would act as my transit visa. A dedicated line for Business Class passengers was available at passport control, and passing through it was a breeze. Once through, I headed over to the Hilton hotel desk, where a friendly gentleman greeted me. The man who turned out to be the shuttle bus driver, later took me out to the van for the 20 minute drive into town.
Once at the Hilton Addis Ababa, I presented my hotel voucher along with passport and HHonors Gold card at check-in, in exchange for a room key and vouchers for lunch and dinner. An upgrade to the Executive Floor was also given.
Given the ungodly departure of my flight ex-Dubai, I slept through most of the day, not bothering to leave the hotel. I did make a visit to the lunch buffet which was fairly reasonable. Various western dishes, along with traditional Ethiopian food (yes they had Injera bread) were on offer, as well as various salads and desserts. I found some of the food to be a bit bland, but most of it was nice and edible. The beef was a bit chewy, but from what I understand, the Ethiopians enjoy a bit of a chew when it comes to food.
The evening was spent in the Executive Lounge with a few glasses of wine, before the shuttle bus driver met me up in the lobby again at 8.00pm. The drive to the airport took slightly longer due to traffic, but once at the airport I found the place to be fairly quiet and civilized. No lines at neither check-in nor passport control, and after an hour in the lounge I boarded my flight back home to Stockholm at 10.30pm.
Apart from the rude and incompetent staff at the transfer desk, I must say that I was very pleased with how smooth the transfer experience went. As a Swedish passport holder I was able to obtain my arrival Visa without providing any passport photos or vaccination certificate, even though I had them prepared just in case. The $20 visa fee was also waived, courtesy of the airline.