Meh.
I went to Big Bang a lot during the peak of my ASU bar hopping days, but never fell in love with the place. It was (still is?) one of the only bars on Mill that charges cover. I don't recall any decent drink specials; domestic beers only.
Of course, everyone's in love with the dueling pianos. Sure it's fun when you're inebriated, but gets old fast. I hear the exact same songs every time I go. I personally guarantee you'll hear 'What I Got' and 'Sweeeeeeet Caroline' at least once.
Overall, a solid veteran of the Mill Ave scene.