First: it’s important to understand that when you’re using ecash from someone else’s mint you’re trusting them as a custodian of your bitcoin. They can rug you.

Having said that, if you trust the mint, then ecash gives you better privacy since you’re trading lightning sats for a bearer token that can be sent out of band (e.g. SMS, email, on a piece of paper, etc).

There are nuances here but for the most part the mint can’t distinguish any of the ecash tokens from one another so transactions within the mint are anonymous.

There are no fees when transacting within the same mint either but of course you have to pay fees when depositing or receiving over lightning.