I struggled with rating this one. I suspect many of the low ratings and negative reviews come from those who didn't watch the series and just representing their partisanship. However, the series is a mixed bag.
In a historical sense, particularly when discussing President Obama's upbringing and early years in politics, the series is very informative and contains footage I don't recall seeing previously. However, the last episode, which focuses on his time as President, I think misses the mark. The subtext is that much of the hostility towards Obama is race-based. Undeniably there is some truth to that, but the assertion misses a bigger reason, which is hyper polarization.
No Presidency is devoid of vitriol, but it has gotten worse in the last couple of decades, especially since the early 1990s. Since Biden's Presidency is still ongoing, I'll defer judgement on it, but Presidents Clinton, Bush, Obama and Trump faced intense backlash and I think one would have a hard time making the case that Obama had it worst. Both Clinton and Trump were impeached and had special counsel investigations, Bush left office unpopular and with is legacy tarnished. Now, to be clear, one can argue much of that was brought on by their own actions, but the fact remains that Obama emerged in pretty good shape relative to his contemporaries and that isn't something the series acknowledges.