For European ancestry, I’ve found it to be fairly accurate based on my family’s genealogical research. My siblings and I used ancestry.com’s databases, which recently updated and refined their results due to their reference populations growing from ~3,000 samples to ~16,000.
According to them, I’m 43% Irish/Scot, 37% French, 14% Spanish and 6% Italian, which is just about exactly correct based on my immigrant background.
Yes, I’m a European mutt... :-)
Yeh, I used to read SA when the science part was more important than the political.