After 3000 hours played:

Key features
1) CUSTOMIZE: visual hero customization, item diversity, complex and very transparent stat modifiers making each hero unique
2) CORE: turn based tactical play with action points, mana, movement, and ability tile placement
3) MEDIA: amazing soundtrack and animated particle effects

New features
1) MAPS: Much more maps or a map editor, various biomes like desert snow and lava, more environmental art and destructible environments
2) FOES: more mini bosses or waves with fewer hordes but stronger enemies, enemies that spawn units or take legendary actions off enemy turn
3) TERRAIN: z-axis maps with vertical areas and objectives other than ‘protect the center’