It's very similar to Diablo 2 indeed, but that's a good thing
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The company behind it took what made Diablo 2 so great and built upon... There's plenty of innovative features which makes it fresh and enjoyable. It also kept that "dark fantasy" touch that so many think is absent from Diablo 3.
It's worth a look whether you're an old school Diablo player or a fan of Dungeon crawler/loot gathering games.