This game brings the thrill that D3 failed to accomplish.
Balance over powered with even more over powered.
Every class is overpowered in their own right
endless pvp options
the fact that you HAVE the option to do many many different and pretty viable builds, with an overwhelming amount of items, stats, synergies etc in your arsenal, the replayability is literally endless with this major fact.
The fact that Magic Finding is actually fun in this game, its randomly generated items, its literally a gamble after every boss, and we always see that unidentified ring and think 'It just could be it..' Usually we get sad when we see a lowly level 17 unique ring, but when that SoJ appears, its just an awesome feeling.
Mix in the overwhelming joy of seeing that HR drop, making runewords, and pvp - its truly a perfected game that has and will age well.
I've had more fun solo playing d2 than I have playing d3, D3 in its own right was fun - for the first week, and only with friends.
D2 has that lovely nostalgia effect that we all love and enjoy.