Playing Arthas has to feel like you are in control of one of the most deadly heroes ever to exist. He can steal the souls of enemies he kills and have them follow him into battle.
You can choose your own Heroic Ability currently in Heroes.
Elite Tauren Chieftain also appears in Heroes. He can move quickly and heal himself. Stage Dive is his heroic ability, allowing him to jump on the enemy from out of nowhere. He also can force everyone to stop and dance briefly.
Abathur from SC2 also appears in Heroes. He can jump inside any friendly hero from far away, allowing him to shoot abilities from inside them. On his own he isn't dangerous at all.
Heroes have different skins that are as simple as color variations or entirely different models. (Diablo + Murloc, Starcraft Uther, Judgement Armor Uther)
Games last twenty minutes.
Battlegrounds provide opportunities to play with friends and a variety of gameplay settings. Maps can be taken out of the matchmade game rotation and new maps added.
Blackheart's Bay requires you to find chests, attack them, collect the coins. You take the coins to Blackheart. Other players are treasure goblins, carrying coins and trying to avoid you.
The Haunted Mines requires you to kill the undead underground and collect their skulls in a PvP/PvE dungeon. There is a boss that has a lot of skulls, so there is a big teamfight around him usually. Once all the skulls are collected, a golem appears for each team. The size of the golem depends on how many skulls you collect. They move across the map and smash things, so you have to choose to defend your or go and attack the oncoming golem. Wherever the golem dies is where it respawns next time it comes to life. Your team wants to keep it far away from your base.