Heroes of the Storm is a Multiplayer Online Battle Arena (MOBA) released officialy June 02nd, 2015.
I've not played other MOBAs like League of legends. My experience with that genre comes from similar style maps back in the original Starcraft, and the Tower Defense-type maps from Warcraft 3, so my perspective comes from that of someone fairly (if not completely) new to the genre. I won't be examining it as it compares to other MOBAs, i.e. League of Legends or DOTA, only as it holds up as a game on its own.
Overall, Blizzard does manage to make their game fairly fun. I'm reminded of the Starcraft 2 mission maps that had me controlling the hero (or a small group of heroes). Of course, there's more skill choices as is commensurate with the genre. The training mode gives you an adequate introduction to what you're supposed to do, and I found it amusing to go through as well. It's worth going through, if you don't know what you're supposed to be doing, or if you just want to see some of Blizzard's characters from different franchises react to eachother. Short version, though: level up, destroy the enemy core. There's alot in between, but that's the focus.
You start by picking your hero. The game is run by microtransactions, so if you want continual access to a hero you have to purchase that hero. You can use gold for alot of things, which you earn by winning matches, completing daily quests, or leveling. Everything also has a real money cost, since that's how this game pays the bills. Some things can only be purchased with real money. The good news is that if you can't buy a hero right off (or don't want to) there's a set of heroes provided for free access every week. You don't get to keep them if you haven't already bought them, but you do get to level them. They keep that level even when you lose access to them, so they still have the same progress when you next get access to them.
Once you have your hero, you can can choose to go into Training mode, play with (and against) other players, or you can choose to play against the computer. Each map is 5v5, so if you choose to go against the AI, you'll also have AI allies to fill in the empty spots. You'll be thrown to a random map with its own objectives that, if completed, will typically help tip the balance of power into that team's favor. You'll be killing waves of auto-generated minions. You don't build anything yourself, but you've got to keep your buildings from being destroyed as you go about destroying your opponent's base, and defeating the opposing heroes. If a hero is defeated, it takes time to respawn back at your Nexus. Try not to get defeated as you go defeating the enemy heroes, as it takes longer to respawn as time goes on.
As you fight your way to the opponent's base, your hero will level within the map, providing access to new abilities every so often. Your hero also levels outside of the map as you gain experience, unlocking access to more skills to choose from within the maps, new skins and colors, and some gold. You also level up, providing some perks (such as unlocking another free character rotation slot) and some gold as you go.
I've been playing the versus option, and the AI for the computer opponents (and allies) doesn't just roll over. If they've got the win in hand at your core, the enemy AI's not going to be distracted by you attacking their core at full shields (or at least it wasn't for me) and likewise, they're not going to waste time attacking heroes that are attacking them if it's only a few more hits to victory. The friendly AI generally responds to the minimap pings, but not always,... kinda like real people, hehe. I find that the allied AI doesn't always take the opportunity to take control of the summonable map-specific boons. Whether that's good or bad depends on your preference (do you want to trust that to the AI?), but the AI does seem to give up the opportunity alot.
The biggest drawback is that this game runs on microtransactions, but one can hardly complain when you know that's what you're getting when you begin. You get to play a random set of heroes for free each week, and you can earn gold to purchase heroes, but if you want the fanciest skins and the fanciest mounts, you have to shell out real money. No doubt there will be new heroes, new skins, and new maps. They've already added one new hero in the Crusader Johanna. Those will cost money (and if we're lucky, most of it will also be offered for gold; Johanna is available for gold, for the record).
Overall, Heroes is a fun way to spend 20 or so minutes. After trying a few heroes, I can see the appeal in the genre, though my own interest in giving it a try is mostly as a Blizzard fan. I enjoyed Raynor, Diablo, and Tyrael (Tyrael being my favorite right now), and found Tychus and Lili interesting to play. I tried Elite Tauren Chieftain, but was not excited to spend more time on him than I had to. If you're interested in dabbling in MOBAs, this is a fun one to start with.