I’d say Illari has been the least impactful and loved hero launched in OW2 so far. She’s far less popular than LW for sure and far less beloved than pretty much any of the other OW2 heroes. She probably could give Sojourn a run for people not really being into the hero while Sojourn at least is played often for a fun kit and had some lore importance.
And I’m not saying this as a Illari hater, I personally don’t hate her. But she seems to be the least popular of the OW2 launches. I think the gloomy and miserable direction they took her character didn’t help her get much traction. Freja also is suffering from being just being a bland grump, but her kit is keeping people interested and her ties with Emre.