I had me some blueberry beer made at a local micro brewery.
It was sweet/sour, fruity, and STRONG!!! The blueberry taste was quite natural.
Can't say as I liked it much. To me, beer should remain, well, beer. I can see mixing in flavors for the sake of novelty or out of boredom, but it becomes something other than beer. Like all those cocktail-tinis, they may contain vodka and come in a martini glass, but they aren't martinis and someone should have given them new names.