The HE is very good in the case of.... a tank is rear towards you so long as it isn't a german, russian, , it's a german or american tier 7 or 8 light tank, it's a french, american, british, or swedish heavy tank that is facing rear towards you, or if it's french or the Yoh series, side on as well. Of course there's the squishy TD's that you occasionally come across, but uh.... the HE pen being pretty basic doesn't really help it be any more niche than any other HE shell in the game.
The gun is as standard as it gets for a TD, the HP pool is as bad as the Charioteer's and ISU-152's, with the only thing making up for that is it's armor that's tier 7 and bad player resistant, as well as the reactive armor.
The mobility not being bad, and it having super consumables is honestly the only reason the tank isn't in the same boat as the ferdinand.