Starbucks is a great corporation. If you're traveling in a strange city and want a cup of coffee, you know what you'll be getting at Starbucks.
But if you live in New Haven, why not get a good cup of Koffee? - and everything Starbucks can't give you: local community and culture. Koffee has a similarly peaceful and attractive feel, but is decorated with revolving art by local artists - often good, sometimes spectacular. The baked goods are fresh baked by the guys and gals serving your coffee, and are uniquely delicious recipes. And speaking of the baristas, they're skilled and snarky, in just the right mix of politess and color as they pull your espresso shot. If you get your koffee and stay, your fellow customers will be Yale students and professors, studying or discussing a wide range of topics, local professionals trying to take a quick break from the office, young mothers with their babies enjoying a bit of social life, and, in the afternoon, school kids and their parents.
Wireless is free, and there's always reading material (and a few board games) on hand. Patrons are friendly and welcoming of newcomers. The muffins are to die for.
Also - Vegan friendly! Soy options (and prepackaged vegan cookies) abound.