Kane was probably overrated by people who liked him (ie, most Spurs fans) but underrated by people who didn’t. Not a flashy player because he’s not fast (relative to other guys) but a very good goal scorer who always put himself in good positions to poach goals and a very underrated passer.
Related note, I’ve been entertained this year hearing stuff about how Kane is as good or better than ever which is likely solely because he’s scoring more goals. Nevermind that it’s in a league that’s not as good as the EPL. With Spurs he never finished higher than 10th in the Ballon d’Or (which was probably fair) but this year he’s been projected as a top-5 finish.