That's not to say he never gets anything wrong, he and his researchers aren't steeped in the subject for their whole careers so they'll miss things. He is biased towards the exciting stories and sources, but usually qualifies them with "I'll tell you this fun story but historians disagree about X Y Z because of A".
I'll have to look into the criticisms but my impression just from listening is far better than any other pop history.
But you'll be happy to hear that "sometimes uses outdated sources or oversimplifies stuff" is a common criticism of basically all academic history written outside of the last 20 years, so he is in decent company.
How so? He seems to be pretty upfront in talking about his sources, quoting from them, and saying repeatedly that he's a journalist and not a historian.
But talking about the people who were in that event, leaning heavily on eyewitness accounts and primary sources, all of that makes the events come alive. I think both are valid and important viewpoints on history. I think history in school would be a lot more interesting if it took a similar approach.
Looking at an historical event at more of a ground-level is nowhere near the same thing as giving outright incorrect information.
Carlin's podcast series are much, much longer than Gladwell's typical podcast treatments though, so at least it lets him include a lot more details.