The problems you mention with that beer sound similar to the ones that plague the wretched SA Cherry Wheat. It tasted as if the "cherry" flavor derived from bad cough drops! It could well be that the BBC is employing a similar strategy for the BW.
I'll have to look for that Longtrail's Blackberry Wheat. In addition to the Blackberrry one that I bought, I also got a beer called Hemp Ale. It's not bad, though I think it tastes better if you're eating something while drinking it.
For the record, I tried and voted on the beer selection this year for Sam Adams. I chose the coffee stout over this one, but neither was very good. But hey, those new imperial series beers coming out seem like they are worth looking forward to.
I actually selected the Blackberry over the coffee stout, however I agree that neither one of them was very good. I think the day I had the samples was very hot, and the mediocre shot of blackberry beer was a bit more refreshing than the coffee.