He's the perfect two-sided coin of gaming.
On one side, he's a visionary, coming up with innovations well before their time and attempting to do something that no-one else would dare to do (let's face it, if Black and White were released for the first time tomorrow on the Wii it'd sell like mad). He's been prepared to break the mould in his own ways to produce games which, criticise them all you like, it's quite hard to justify calling "derivative".
On the other side he's a hype-spouting monster, who is the main reason behind the slating of his own titles, the claims of ground-breaking new features that never materialise in the release have cost Lionhead badly and given many a drastically negative view of the company as a whole.