I think his chat-show host persona can be grating when he tries to overshadow his guests (The Tarantino interview) or be as hacky as possible (the man had Johnny Depp and Tim Burton on his show and the pink-suited f'ckmouth wanted to go on and on about Depp's facial hair).
But I liked what he did when he took over from Barry Norman, and went all Kermode-like in his interviews, and he showed some good tastes/critiques of films, and, I liked whatever of his DJ stuff I caught.
When he's reined in and behaves like an adult he's intelligent and all good, when he's given license to ad lib and forces the need to be wacky and Out There with the 'what'll-this-kerazy-guy-do-next-in-pursuit-of-must-watch-tv' he comes across as a phoney schmuck.