I was connecting in Addis from Frankfurt to the Seychelles recently and so had a chance to enjoy the Ethiopian Airlines lounge.
After exiting the aircraft, there is a staircase leading from arrivals to departures for connecting passengers. The staircase comes out right in front of the lounge. However, once you show them a Business Class boarding pass they whisk you through to the second lounge which they keep just for Business Class.
The lounge whilst large got pretty busy fairly quickly. There are multiple seating areas:
There was a range of hot and cold food items, juices, water and tea/coffee. There was free Wi-Fi although it was terribly terribly slow and glitchy.
The room became very busy as people arrived to connect and I left to find my gate.
There is a priority security line at most of the areas to get to the gates, although this was not always very effective. All the gates are joined together post-security so you just need to get through wherever you can and walk to your gate.
You do get a good view of the waiting planes:
Unfortunately, my plane was located at a remote stand and we had to board a bus to get there: