I'm not entirely sure about the story in Diablo 4 Gold. On the one side, it shows plenty of respect for the history of the franchise that picks up where Diablo II left off and setting the scene for what's to happen when you play Diablo III. There's more to learn about the civilizations and cities of Sanctuary, and longtime fans will appreciate the appearances of characters like Xul the Necromancer as well as the King Leoric who is from Tristram.
However the storyline itself is an almost beat-for beat replay the storyline of Diablo II. You'll assist a group of woodland rogues. You'll also reassemble an iconic staff on the desert floor, fight off hostile Shamans in a swamp, climb a mountain with barbarians -If the game is Diablo II, you've literally had all of that before. The story beats in the new game consist of "find the MacGuffin to destroy the MacGuffin" repeated multiple times. I'm also wondering if Blizzard will follow the same strategy to expand new areas to the game in the future.
How Diablo Immortal looks and feels depends on the version you're playing, whether it's the full release version on Android/iOS, or playing the open beta on PC. (Your save data is synced between both, meaning you don't have to commit to one cheap Diablo 4 Gold or the other.)