I've been to W Burger Bar quite a few times since it's near my work. Due to the $9 pitchers of Pabst Blue Ribbon it has quickly replaced Pogue Mahones as our place to go for a quick one after work.
The beef burgers are pretty good but could use a little more seasoning. I like the fact that you can pick from a large variety of unique toppings like Garlic herb mayo and cilantro yogurt. As far as gourmet burgers go this place is my favorite (but i haven't tried them all yet). I didn't really like the turkey burger, only tried it once. Friends all enjoyed the bison burger just as much as the beef burgers but i haven't tried it myself.
The staff are really friendly even though they have to put up with a lot of rowdy customers late at night.