Heroes of the Storm Info and ImpressionsTL post summarizing some of the game
Lifted from the article
The general game mechanics are vastly different than similar games in a few ways.
There are no items, there is no shop. You differentiate your hero by choosing feat-like abilities every so often (levels 1, 4, 7, with 10 being an activated ultimate and 20 being a different ultimate - I forget when in between those). It's things like +20 attack damage or 10% attack speed, with some of them also having cooldown reduction properties or adding to your q-w-e abilities. Each of these are dependent on your hero, there are some that many heroes have but also unique abilities (Diablo can choose to get a built-in Radiance at some level).
You get 3 of your skills (plus a passive) at level 1 with the scaling of them depending on what you choose from leveling, and gain your last at level 10.
Experience is shared throughout the team, no matter where you are on the map. You do not get extra experience, or any currency, from last hitting. You get experience while you are dead. Your team will always all be the same level.
Hitting B will bring you to the fountain as with League. You also have a mount that you can use when you are out of combat that gives +20% move speed to run around the map. There are no TP scrolls.
There are certain jungle creeps you can kill, and they will summon mercenaries that will march forward towards enemy towers. They are not controllable and seemed strong.
Towers have a limited number of bullets, something like 16-20 and they can run out of ammo. They restock over time but an extended siege can run them dry.
At the end there is a "Features" screen which lists "unlock heroes and skins" which leaves me to believe this will be similar to LoL in how to get new heroes, rather than having only cosmetics as unlockables like Dota.
The alpha build has 2-3 different skins for each hero as well as each mount (screenshots of some below).
I played 6 different heroes and they all had gap closers so I think this is a common trait. Also one of the supports has a teleport that can go to anywhere visible on the map.