There's a thin line between confidence and pomposity tbh. You need the confidence to be able to address a group of skeptical people ... ... but that can easily be perceived as arrogance.
Saw him live a few times in mid to late nineties and he was excellent. Thought his first few books were good also. Not seen him again live or read any more of his books for years.
Saw him live in Reading circa 20 years ago. Like most I thought he was a bit of a prick but would admit that was one of the best, if not the best comedy gig I've been too.
In terms of blackadder and young ones he has left an indelible mark on british comedy. I suspect he is a bit high brow for some hence the dislike in certain quarters