We stayed at La Source Guesthouse for 6 nights across our trip in Ethiopia and thought it was great value for money. The staff were welcoming, friendly and helpful, giving us directions and good indications of how much things should cost.
The room price includes breakfast and airport transfers. Breakfast included yummy cheese pizza and various juices (try guava juice in Ethiopia - delicious!) and the staff were happy to whip up an omelet when we came down late one morning. We had four airport transfers across our stay and they were always on time and even drove out of their way so we could pick up my husband's wallet we'd mistakenly left behind at a friends.
The cafe connected with the guest house does great food, especially the pizza, good coffee and yummy juices.
The room wasn't poky, had a comfortable bed, no bed bugs, and a TV with cable. The shower was hot!
My only suggestion is if you like a dark room to sleep in, get a room at the back, as the curtains aren't very heavy in the front rooms and there is quite a bit of street lighting.
We booked through this website - http://www.ethiopiahotelguide.com/la_source_guest_house - including partial upfront payment, and all our dates, pick up details and payment was managed perfectly.