The Pillowman is one of my favorite plays. Strange that it never ran in the West End til now. Some of the reviews are indeed pretty bad though, and the general consensus seems to be that Lily Allen just wasn’t up to the task of such a demanding role.
The Williamstown staged reading seems interesting, with both Katurian and Tupolski played by women. I think that if you are going to have Katurian played by a woman, you kind of have to have Tupolski be a woman too, otherwise it would be hard to laugh at Tupolski’s (darkly) comic bits. Maybe that’s part of the reason why this London production evidently didn’t really work.