u/Bodark43 has a good rundown here.

A few things I can add - while it does add additional, non-traditional perspectives to a narrative American history, it notably leaves out natives and their voices (there is not even a named Native person in any of the sections covering the 20th or 21st centuries). Christine Delucia, who is a professor of Native American History and a former student of Lepore's wrote a critical review of Lepore's book to this point. That's worth checking out because Delucia and Lepore have differences in historic methodology that led to the choices made in Lepore's book that Delucia criticizes.

I honestly only read the first chapter of Lepore's book, and it did have a peppering of factual inaccuracies that are presumably from Lepore writing outside of her specific field of speciality. She does write a number of doozies that seem to come from Jared Diamond, such as:

• She discusses Ptolemy's writings about how to project a globe onto a flat surface, but then writes: "medieval Christians, having dismissed the writings of the ancient Greeks as pagan, had lost much of that knowledge." This is a very weird thing since medieval Europeans in fact did study the writings of pagan ancient Greeks that they had (or could obtain from other areas), and an astronomical model based on Ptolemy was the standard for Europeans until the 16th century.

• Regarding 15th century Chinese sea voyages and their end, she writes an old saw: "China was the richest country in the world, and by the late fifteenth century [it] no longer allowed travel beyond the Indian Ocean, on the theory that the rest of the world was unworthy and uninteresting."

• "Very few people or plants or animals moved from the Americas to Europe or Africa, at least successfully." I suppose if you totaled up the number of species transplanted to the Americas versus those transplanted to Afro-Eurasia, maybe it's true. Nevertheless, the successful American plant transports have become some of the largest food sources in the world: maize, potatoes, cassava, and sweet potatoes, to say nothing of tomatoes, squashes, peanuts, sunflowers, peppers, pineapples, vanilla, and cacao. And many more.

• In a related vein, she leans very heavily into the virgin soil hypothesis of disease among indigenous peoples of the Americas, namely that because of "the isolation of the Americas from the rest of the world for hundreds of millions of years" (which is a super yikes error right there, and weird because she mentioned the Bering Land Bridge earlier) they had no resistance to the diseases brought over and died in the tens of millions right after contact. This hypothesis has fallen out of favor, for a variety of reasons detailed by u/anthropology_nerd in this answer.

• She writes "In 1492, about sixty million people lived in Europe, fifteen million fewer than lived in the Americas." We should be very cautious of any sorts of population figures from periods before modern censuses, and her figure for the Americas of 75 million is not the highest estimate (which would be something like 112 million), but definitely William Denevan's "consensus count" not the median estimate either of around 50 million. All of these numbers have been sharply disputed over the decades. This is an example of her not being wrong per se, but she leaves out that there is still a wide range of estimates and disagreements in favor of presenting a number as an accepted fact, and its apparently in service of a point that there were more people in the Americans than in Europe in 1492.

Anyhow - does she write with a bias? All historians do. All historians make a choice what to include and what to leave out, and Lepore is mostly including items that built a history of ideas (specifically around a history of identity, and American identity), and has made selections accordingly. She's primarily trying to present a work to give an American historic background that can provide a useful sense of civics to the American reader, and she also intentionally kept footnoting to a minimum to make it more accessible to a general readership (none of the items from the first chapter bar the virgin soil item have footnotes).

Overall, if you need an introduction to American history in a single volume narrative history, and one that tries to look at history outside of the Great Men, battles and diplomacy narrative, this is still probably one of the better choices, despite its real flaws.

u/Kochevnik81 makes good points.

In my old Penguin History of England series, they had J.H. Plumb write the volume on the 18th c.- where he knew his stuff. They didn't come to him and have him write that and Stuart and Tudor England as well. If he had, he would have made mistakes. I think that Lepore was greatly hindered by having to undertake a one-volume history, and her mistakes with Native American history are typical of what you'd expect from someone who has not spent much time in that field ( and it seems a very fast-changing field). So, she's getting knocked in the way you'd expect: specialists coming forward to point out her errors, and to complain she's not giving their field nearly enough space in her work. . H.R. Trevor-Roper once remarked that, instead of standing on the shoulders of giants, modern historians were all standing on little molehills, jealously guarding them from others. She wandered onto someone's molehill, got some things wrong about the molehill, and didn't say the molehill was important enough. Not that Native American history is trivial, by any means. But she's only got the one life for research.

In the best of all worlds, this book would have been at least three volumes, divided up among scholars more specialized. As it is, it's OK for one big book. It has some problems, but it's really better than most anything else current out there. Importantly, it's in the niche that has been occupied by Howard Zinn's A People's History of the United States, and there really is no comparison. Zinn was not a historian, Lepore is.