He was quite an accomplished racer, too, hence his 'inside' knowledge. Never afraid to voice his opinion, and to change it when appropriate - virtues not at all that common, whether in journalism or in all walks of life. He will be missed.
On the several occasions that I managed to usually almost literally be run into by Robin Miller given that he always seemed to be motion, I found him to be exactly what you saw on the screen and what he wrote.
On one such occasion, I managed to remember to ask him about a certain A.N. Other (A.K.A. "Buford" here...) and after maybe a second or two he launched into a quick few stories about John. Then he asked how in the world (it was actually, "How in the ****!") did I happen to know John?
One of things that I liked about Robin Miller was that while he certainly had opinions, whether you liked them or not, they tended to based upon a wry view of the world that he covered. An informed view of that world, I should add.
Nigel is correct that Miller would never be tolerated in the F1 world, and the same would apply to that of the NASCAR universe, where passing a sycophancy test is apparently a requirement for press credentials -- and ditto for F1, for that matter.