I have never made a fruit beer per say, but I have read enough to know that you should add the fruit to a secondary vessel after fermentation completes, especially if you want to retain as much fruit flavor as possible. Primary fermentation is too violent and will chew up most of the fruit flavor.
I have seen recipe's on this forum for blueberry wheat beers, and others seem to like them. If I were going to make a fruit beer, it'd probably be a wheat. good luck.