Full disclosure: this was my first time trying Ethiopian food, but I did read up on it and go with someone who'd had it a couple times.
I didn't find the injera to be sour at all, although it was certainly spongy. They didn't give nearly enough napkins considering you eat with your hands - like seriously, one napkin and one wet wipe per person? Am I supposed to use the injera?
The food. I got the Mama in the Kitchen with chicken and I didn't like it. The flavors were unappealing and not nearly as intense as they should have been (food smelled MUCH better than it tasted), the textures were weird (grainy, saucy stuff just smeared on the injera), the vegetables were really limited (just starches and legumes, basically), and they didn't give nearly enough injera. I also felt that the stews and such were watery enough that the bottom piece of injera was basically inedible after you finished one or two samples of food. I wanted to leave right away when I tasted this, but I hate paying for food and not eating it.
Service was fine, if brusque and inattentive. Place is clean but has mainly booths. Outside seating area looks really annoying and meant there were a lot of bugs around. Would I come back? Nope.