Sharp but deep dark chocolate and roasted peanut smell. Acidic taste starts the mood and lingers a bit before the bitters of chocolate and a mild peanut flavor start to develop. Surprisingly acidic.
The peanut butter flavors are interesting but you can tell the underlying porter has some flaws. It's bitterness is annoying and it carries a sour and somewhat metallic flavor.
I didn't know what to look forward to here, because the other P-51's have been horrifyingly bad. So this turned into a really nice surprise: lots of peanut butter candy aroma and flavor, which spreads out over the tongue in an appropriately oily fashion. It really cuts the sour aspect of the base porter, which is still clearly there but with, well, grossness neutralized. Not quite as good as other peanut butter beers I've had, but still solidly enjoyable.