Actually, that would be incorrect.
He is a good drummer. He is not a GREAT drummer. Big difference. People today are so over-reactionary about everything. If one is not the most revolutionary 10000bpm blastbeat factory you suck.
Apparently, there is no such thing as a middle ground anymore. Either a person is GODLY at what they do ( and F-you if you dare to think otherwise!) or they utterly suck ( and a double F-you if you think otherwise!)
The concept of fair, average and good are completely missing from the modern mindset apparently.
That said, all one has to do is listen to Ride the Lightning and And Justice For All, and see Lars is certainly capable of skill. And his double kick work is very good, as is his stamina. It's mostly his Snare/Tom work that is lacking. He occasionally come sup with a cool fill, but more often than not, he defaults to very standard blues/rock snare/tom work, just sped up.
In truth I would say his biggest "crime" is being either lazy or just not very imaginative as a drummer.
But he is by no means a bad drummer. It's just people pretty much fel the need to overcompensate on everything, and people also love to roll the whole Napster thing into it and pretty much take even more points away from his actual skill just because he is a douche.
Of course, if we applied that scale to all musicians, Dave Mustaine of Megadeth would be the worst guitarist to ever live.