Black IPAs can be thought of as a hybrid of IPA and porter that originated - somewhat contentiously - in the pacific northwest of the United States which gave rise to the alternative name Cascadian dark ale.  Brewers come at the beer from two different angles.  Some look to give a pure IPA flavour and aroma profile, but with black colour which acts as a sort of trick of the mind when the drinker takes a sip.  Others bring a little bit of roasted malt to the party as an accent to the otherwise hop dominated flavour profile.  Either way, black IPAs are delicious and worth a go even if you "don't like dark beer".