H&S is a great narrativist rules-light supers RPG. Its scaled rank system for attributes and powers works well. The game's core mechanics for character motivations (called drives) and stress (emulating physical, mental and social setbacks) brilliantly support the superheroic genre. H&S oozes with potential for some fantastic role-playing and story-telling in any style of supers game.
However, some elements of the game feel somewhat too sketchy for my taste. Character creation and advancement come to mind, the author meant them to be free-form but I think both elements could benefit from a bit more structure. Some of the rules should also be clarified although the book contains a very useful example of play.
Hearts & Souls is a rough gem that could really shine with a little polishing but that sure didn't stop me from making it my supers RPG of choice.
[4 of 5 Stars!]