Why ecash is so much better than your normal custodian:

- it can be audited as easily as any custodian
- users have way better privacy
- users can make payments peer to peer
- it supports smart contracts
- it works half-offline (sender or receiver)
- it's more efficient to run
- individual users can't be singled out: either censor and rug everyone or no one

Why it's worse: 
- if the user vanishes, there is no way to recover their funds
- users need seed phrases and recovery of lost funds is more cumbersome than a simple username + password login

(Both cons are basically a consequence of privacy)