People keep repeating that ISU-152 can bounce but seem to ignore that even when it bounce it does damage. It actually has one of the highest deflection damage in game.
It does 120 damage on deflection up to 162 with "mark vehicle".
On top of that it comes with 400/350/300 penetration skill shot.
Probably because SU-76, a 70 fuel light vehicle, will do 360 to 420 dmg at the same time wihout mark target.
Also, imo ISU-152 with it HE round are good wiping machine consider Axis infantry are mainly 4 man squad, 1 HE shot is usually good enough to force retreat ( if you don't have frontline halftrack ).
I highly advise you to check what Brummbar does to 6-7 man squads of allies.
You also need a retreat after taking 1 shot if it doesn't outright wipe your squad.
This is how expensive AI units that aren't flamers work, if you get hit, you have time until next reload to save your unit.