I got into the Heroes of the Storm alpha recently, and had a chance to play the tutorial plus a game or two. My initial experience is that the game-play is extremely simplified. Instead of other games that have a strong focus on micromanagement (last hitting minions, item builds, etc.), Heroes focuses on the team-based bigger picture. Gold is shared between everyone, kills don’t reward one player above others, and reacting to team pings is the way to win.
I found it a little simplistic compared to games like League of Legends or DotA, but I think if Blizzard polishes the game some more (which they will), it should be a disrupting force in the MOBA segment. With the changes they’ve made to their flagship games like World of Warcraft, Blizzard seems to be banking on the casual segment of the gaming population, which is an interesting gamble to make.