Image quality has improved a lot in recent months thanks to better models. The ability of people to notice these improvements is plateauing because they are not trained to spot artifacts, which are becoming more obscure.
It will be wrong on a lot of details. Basically you would get a market scene that feels 18th century gb, but will use 18th century russian/french/Austrian details, or 19th century/20th century British artefacts, or a mix of both. And the further you go from western places, the higher the error rate is. Basically generating fiction scenes. That's pretty much my usecase, so that's fine, but I won't ever use it to illustrate a historical TTrpg.