D's has so many great things about it, it's hard to pick which one's the best. The whole atmosphere of the place is great, very laid back and everyone there is always enjoying themselves.
Obviously, the beer selection is great. I don't know how many different brews they typically have on hand, but it's a lot. And you're encouraged to go pick out your own beer from the walk-in cooler, even if you're sitting at the bar. The staff there is always friendly and you can sample some of the beers on tap if you're unsure of what you want.
The food is pretty good too. The dogs can be simple or loaded with all kinds of toppings, and are a staple of D's. They also have a good selection on the rest of their menu too. Chili cheese fries - great.
If you haven't been there yet, stop by in the afternoon on a Saturday or Sunday for a great local vibe.