I've been to The Bookstore a number of times over the past year or so and have found the prohibition-style bar to be a fun and refreshing break from the usual Pennsylvanian night scene. Their significant cocktail and beer list is creative (you might first wonder where it is, because it's glued into the first few pages of a book) and includes many off-the-beaten-path selections. (Try an egg-based cocktail for the full experience!) I've also had wonderful luck ordering off the menu; during my last visit, nothing on the menu was really grabbing me, so my waiter suggested I give a few guidelines and let the bartender invent his own concoction... The end product was delicious! More than anything though, the styling of the place really sent me back and before long I completely forget that I was in Bethlehem, PA!
I will concede to the previous reviewer that the staff can occasionally be a little snooty (I would be too if I was a master of the 20's cocktail!) and that the prices are above average for the area, but I still argue that it's a unique experience, that's definitely worth the premium.