Definitely worth the 4 hour queue.
Banksy's art does provoke controversy, but he only says, in art form, what every one thinks. He has a playful, and in some ways immature approach within his artwork- a bong filled with cannibis placed amongst ornamental antique vases, and a vintage gypsy caravan with 'eviction notice' planted on the door.
The concept of the art exhibition was graffiti, vandalism of the art museum, regular displays that had been 'altered' and tampered with: a display of the formation of icicles but with a model of a penis mimicking an icicle, a pleasant landscape painting invaded by aliens. After wandering through the museum, his artwork becomes irregular and inconstant, it seems to blend in and you have to search for it amongst the authentic art pieces.
Many of Banksy's work was most probably missed by most people, thinking that there was no more to the exhibition, I was almost one of them!
I did find it shocking however, during the 4 hours of queue people-watching, to see 2 little old ladies barely un-able to stand, various little children, mums tagging along with their teenagers, and plenty of old men, what seemed to be the type to look down upon graffiti as a "disgusting act of vandalism". Banksy definitely has the most varied fan base I have ever seen.