The worst is that Ethereum showed that if you have enough power, you can reverse what's recorded on the blockchain.

1. This is true for ALL blockchains based on Satoshi consensus. That's how it works.
2. ETH did not reverse anything or rollback any transactions. All the Ether remained in TheDAO contract, so they didn't have to do that. This makes this significantly different than trying to rollback for a Mt Gox theft or the like. This was uniquely possible.