Here are my general thoughts and some speculation regarding libra. Just to be able to say in the end: I told you so.
Don't take anything of the following as a fact. This is just my opinion and expectation.
1) Libra will use delegated proof of stake.
This means that there will be a very few master-nodes. It will be impossible for a normal person like you and me to run a full node. Instead, those 100 companies, which paid 10.000.000 USD will all run a node => 10m USD license fee to run a node.
It won't be truly P2P. Instead, you are required to trust these parties. Trusting 100 for profit companies - most of them are US-based - does not sound like it is decentralized.
2) Data is the new oil.
Facebook is analyzing your habits to place targeted advertisements. These ads aim for you buying a product or service of the advertiser. But tracking whether the user did buy or did not is hard.
Libra is worth gold in this case.
Facebook will be able to track every transaction you make. Every product you purchase. This is worth gold.
3) Reskinned PayPal.
To me it does not like a cryptocurrency which follows Satoshi's spirit of financial freedom. Instead, by using it you will lock yourself into an ecosystem primarily controlled by for profit companies which do not care about privacy at all.