I think that Kefi started out strong when it opened, but is in danger of fading and losing its long-term luster. The Greek restaurant business is a pretty competitive one, as what makes a great Greek restaurant is consistent quality, great service, and good portion sizes (for an example of a place that follows these guidelines and is always packed, see the review for Stephos' in Vancouver). I've eaten there with my family a number of times, and have noticed that stinginess is becoming a hallmark of this restaurant. The souvlaki skewers seem to get smaller every time I go. You need a magnifying glass to find the feta in the Greek salad, which is otherwise overrun with onions. The side order of Tzatziki is extremely small (a few tablespoons), despite its price tag (which I seem to recall is close to $5).
Despite the above negative points (which are definitely fixable), the food is overall very good, notably the souvla (spit roasted lamb) which is out of this world.
I just pray that the owners of Kefi don't try to save a few pennies here and there by cheaping out on things. Despite my 5 or so visits in the past year, I will only give Kefi one more chance. If next time I go there I see more evidence of the above cheapness, then I am done and will not be returning - and I'm sure I'm not the only one out there that feels this way.