They're as good as the originals, Craig, i.e. they track nicely on corners, no nasty surprises, and work well in the wet too. They also seem to lasting well so far, on UK tarmac, as did the originals (7K miles per set).
I've also tried Dunlop, Metzeler, and Michelin across 40k miles on a K, and the Pirellis are still the best overall, with Michelin being a very close second.
My II's aren't yet worn down far enough to know if they 'whiteline', which was my only negative against Mich PR4.