THC2 is one of the most disturbing, trashy, sexually brutal, violent and pointless movies I've ever seen. There's no artistic view in this, and, Mr. Tom Six (Director/Writer), making it a black & white movie doesn't save it either. It doesn't even make it more impactful or gruesome. It's just a wannabe-artistic add-on.
That said, I totally get why it has been banned in the UK, because it has to. If the first one was about a mad scientist, the second takes us in the protagonist's P.O.V, and the latter is nothing but a maniac whom is obsessed over the actual movie and the 'Human Centipede' project. If only that was the only problem though... The man isn't just obsessing over the DVD, but sexually aroused by its content. So his goals aren't exactly the same, I let you guess.
Overall, the film contains disgusting scenes of killing, beating, rape, mutilation and of course gore. Definitely one movie you should avoid, even just to save some precious time. it isn't worth 1h28min of your life, believe me.