Governor Nexus, the name of ENS's new governance contract, brings improvements to the DAO's security and operations.
It adds new proposal types, such as optimistic proposals, along with simple but necessary improvements, like being able to change your vote while voting is open and to cancel proposals (both by the proposer and by anyone else, if the proposer sells their tokens).
One of the most critical points is increasing the proposals' Voting Delay, which today is only 12 seconds (1 block on Ethereum), and the lack of a limit on proposals per wallet (which opens the DAO to a spam attack).