Pretty solidly middle of the road, especially if he doesn't run for reelection as I suspect. He won't accomplish too much in legislative priorities but will pass a few notable net positives, he'll get one Supreme Court nominee who will likely be a reliable liberal vote who serves for a long time, and is unlikely to have any large-scale foreign policy catastrophes in the eyes of historians. The border issues will be a dent on his legacy, but he'll likely be credited with overseeing the successful vaccination effort that ended the height of the pandemic. Probably upper 20s.
I think he ultimately runs for reelection, but this sounds pretty reasonable to me at the moment.
Despite being way too early to make any conclusions.
Truth be told, if the Democrats had larger majorities in Congress, I think he could've been a transformational President. But it is what it is.