You are making me work to find sources I'm sure you already know about Jayjg. 
 *"He has an encyclopedic knowledge of the truly enormous mass of German documentation. A recent survey of leading American and British historians found that a large majority agreed that Irving is a historian of repute." - Prof Donald Cameron Watt 
 *"His skill as an archivist cannot be contested." -  Sir John Keegan 
 *"In the area I am competent to talk about, namely Churchill, although I don't always agree with your conclusions, I am always impressed by the rigor and range of your scholarship ... there are few historians with your record for turning up new and relevant documents." - Prof John Charmley 
 These quotes are all post Lipstadt trial. Just because you don't like the guy doesn't make it right to accept POV appellations