Most of the mass produced stuff is rubbish. If your ever in Europe (Germany, Czech Republic, Belgium) you will get the best beers in the world. For Ales England is the place to go and Stouts make a trip to Ireland for Guinness, Beamish or Murphy's
I found the beer to be a mixed bag in the US. Some of it was very nice (local brews) but the likes of Coors, Budweiser etc were quite weak. There was a couple of dark ales (similar to Guinness) but sweet and served in an ice cold glass which was very very nice.