One side claims the blockchain immutability has been breached by draining the black hacker's DAO.
The other side claims, it hasn't been as there has been no rollback of transactions. In that view, it was just an additional special case rule added to the code that removed the usual restriction for one specific address.
Whatever side's opinion you share, there is one good thing that has achieved by this hard fork. The community has been split along those lines and the group that went Ethereum Classic is for the most part no longer involved with Ethereum.
Besides small bickerings on Twitter, there is no drama about this anymore and the Ethereum community is no longer concerned about this event (although not the obvious problems with the complexity of smart contracts but that is an on-going effort).
Imagine if Bitcoin would have split up along the SegWit / Big Blocks lines. We wouldn't have had a standstill for 3 years and we would have been spared that constant drama.