Generally considered - Urien is ok, but doesnt justify his cost, as is typical with named special characters. He is ok with Grotesquery and looks nice there, barring, let me say again, his very steep cost.
Generally he is just more killy Haemunculi. And tougher, but, things that Grots do well against, they wont need toughness and additional killiness of Urien, and things that smash Grots - Urien wont help there.
The Dance of Death begins - embraces, caresses, and kisses,
The Harlequin loves you as you fall over in pieces!