It seems appropriate to start a Heroes of the Storm review by talking about what it isn’t, rather than what it is, because if nothing else it will shine a light on the elephant in the room, then gently usher it out.
Heroes of the Storm is not League of Legends and nor does it try to be. If you like the 45+ minute games, myriad itemisation choices, long laning phases, huge time investment needed to understand the game, and the last-hitting mechanic then this is not the game for you. Nor, moreover, is it meant to be. If, however, the above has served to put you off before, or indeed means nothing to you, then it may just be the entry to the genre you’re looking for.