I watched most of Batman '89 last night and Keaton was spot on in his portrayal of Batman. Yeah, the suit looks uncomfortable, but nobody is going to look 100% cool (facially) when wearing the cowl. They will always either look too small or too chubby. But his performance was amazing.
He's is to Batman what Sean Connery is to Bond. He defined it, and though I feel Bale is the better all around Wayne/Batman, it's not really a slight against Keaton. Sort of like those who think Craig has become the best Bond, but still love Connery's portrayal. I'd say those two are the only ones who have ever done the character real justice.