Online reservations at Abyssinia Market Cafe can only be made directly on their website.
My first visit to Abyssinia was w/2 friends on a Friday night around 7:30PM. When we got there it was packed, and we were told it would be about 5-10 min before a table opened up. We took a seat in their waiting room. In the meantime, three people walked in, stated that they had a reservation, and were directed to the table we were waiting on. #1: Make a reservation #2: State that you have a reservation. They won't check with you. My second visit was outstanding. Went on a Friday night around 7:00PM. It wasn't packed and we were seated immediately. The service and food was great!
The food was great and some of the best Ethiopian food in Denver. Unfortunately, they only have one person to wait on tables, seat people, bus tables, etc, which means that service can be really slow, especially if a big group sits just before you get there.
Once I found the correct door to enter through (it's actually the brown door in the middle of the building) I was a little surprised by the decor. The food and service definitely made up for any misgivings, and made for a fun dinner!