potions have a channelling time, can be interrupted, and you cannot attack or move while channeling a potion. they do however recover MORE health and mana than the full 10 seconds from HoL.
the reason why Shield and HoL seems abusive is because you get to keep fighting (in invulnerable God Mode) while you're recovering a gigantic amount of health+mana.
what alot of people don't realize is that even though you can't damage or debuff a Shielded Demigod you can still stun and interrupt them. please do so if you see them activate a HoL.
my opinion is that its not imbalanced or problematic at all. its one of the more clever strategies in the game and players should be rewarded for being clever.