Well, you covered the "Has Character Building" part while adding the fact that character progression is even more prevalent with Skill Gem progression, Item upgrades, Crafting upgrades. Your character will be your character. The crux of an RPG, unlike D3.
As a loot game, it is an Item-Based Economy meaning no gold. What this means is that every item in the game is useful, so even if you get trash, you can turn that trash into item currencies that other player's might want. Also, crafting makes every equipment viable. You can use transmute currencies to craft the ultimate weapon from a trashy white item.
As a dungeon crawler, maps are truly randomized as opposed to large pieces of map slapped together like in D3.
I personally like the combat better because it is Spam Skills rather than D3's wait for cooldowns before engaging Champions. It is a Hack and Slash action genre, not a Wait-For-Cooldowns genre.
Edit: Oh yeah, I forgot. Ladders. The feature that makes these games competitive. D3 doesn't have one.
