In a nutshell, come here if you want to dine or if you only want drinks during happy hour... NOT for the happy hour food.
Let me start off by saying that the ambiance is great: excellent lighting, decor, place settings, etc. The bar area is like a classy sports bar and the noise-level is at a point where you can still have an intelligent conversation. The food in the dining area is good and the service is solid. The GB home brews are also pretty smooth and only run around $3.50 for a 22oz glass during happy hour.
The happy hour food is another story. The Mediterranean Flat-bread and the Asian Fusion Combination are not only small, but they are also mildly gross. The service is also very favorable to the regulars.
After you go to the Yardhouse for their happy hour, it's hard not to compare the two due to their physical proximity and since they have a semi-similar look. However, the Yardhouse has better food, bigger sizes, and better happy hour deals. But, GB is a decent stop if you need a break from the Yardhouse.