The real Durban poison does taste like anise (licorice). In fact, its famous for that, though some variants have been described as tasting like mint or menthol.
Not only does it have a unique taste, but the real Durban poison is potentially one of the most potent landraces around. High Times magazine just rated one cut of this as a "top ten most potent" strain for 2012, clocking it at over 20% THC. See here at about 1:36:
[video=youtube;gVAYmUBGkj0]http://www.youtube.com/watch?v=gVAYmUBGkj0[/video]
Here's the link in case the video doesn't play here:
http://hightimes.com/video/mike_hughes/7584
With that kind of potency potential, its probably called "poison" because its easy to overdose and get all the bad side effects that sativas are known for like heart racing, paranoia, vertigo, and perhaps even nausea.
Its been a few years now, but last time I was in Amsterdam, lots of the coffeehouses had the real deal Durban Poison from Africa on their menus.