Libra uses the Calibra wallet, built by a Facebook subsidiary and integrated exclusively with Facebook Messenger and WhatsApp. While marketed as a solution for the "unbanked" masses, Calibra won't be available at all to about 35% of the world's population, who live in places where Facebook has no presence or can't operate unchecked (this largely means China and India). The population that will have access to Libra, then, is disproportionately Western and Caucasian. So much for the masses.
A wallet developed by Facebook and integrated with Facebook apps is the definition of centralization, and users can have no expectation of privacy. Facebook wants to know both how you spend your money and how much you spend!
The projected initial transaction speeds are 1,000 transactions per second (tps), which is faster than bitcoin but still a fraction of what post-blockchain technology offers. Libra will initially take at least 10 seconds to confirm transactions.
Libra is centralized and currently permissioned --meaning it's closed-doors and only those people Facebook or their partners allow inside can be part of the process. Ethereum, bitcoin and most blockchain currencies are decentralized and permissionless , there is no authority deciding who can or cannot be part of the network. Libra's "validators" will only be from among the 28 partners, which include Visa, Mastercard, PayPal, Ebay and others.
Permissionless is their ultimate goal, but according to Libra's own Whitepaperthat will take at least five years and even at that point they won't have solved blockchain's fundamental problems:
” We do not believe that there is a proven solution that can deliver the scale, stability, and security needed to support billions of people and transactions across the globe through a permissionless network ," the 50-plus engineers and scienists who wrote the Whitepaper conclude.