It is centralized and same with other altcoins that's being run by a certain company. It would help bitcoin somehow by tagging itself as a 'crypto' because bitcoin is a crypto as well. There will be no ICO but it has a wide range of partnership, yes real partnership so it will have its own usecase. I think this is just another the same stablecoin.
Based on initial articles about facebook coins, facebook will create a stablecoin. But, it's not yet confirmed where it'll be backed from. Stablecoins as they say, is better than altcoins. Let's wait few more days for the official details of Libra.