Dashen's yemisir wot (red lentils in berbere sauce) is the best that I've had anywhere. It has a lot of flavor, but it isn't overwhelmingly spicy. Other selections are fair to pretty good.
I'd recommend the yemisir wot, or especially the vegetarian combo platter, which has all of their veggie selections, to anyone new to Dashen. The combo platter is enough food for two people (unless you're really hungry), which is another plus, in terms of price as well as the fun of sharing a good meal. I believe that all of their vegetarian meals are vegan, given the Ethiopian rules for fasting.
Drink prices are also quite reasonable. As of this review, most import bottles are around $3.50-4.00, and tap beer (Sam Adams (?) or Guinness, for example) is about $4.00 for a 20-ounce mug.
I also enjoy the casual atmosphere and the variety of live music that might be playing on a given weeknight. It's also a plus that they've donated food to at least one CAA potluck.