Well, for one thing you can use it in place of your crypto wallet address. Why? If you register with ENS your crypto wallet address is part of the registration (much like your web2 site’s IP address is a part of your DNS entry) so you can just have crypto currency sent to your web3 domain instead of that long crypto wallet address.
https://cointelegraph.com/explained/the-concept-and-future-of-decentralized-web3-domain-names has a good (maybe a bit too detailed) explanation of how web3 domain registrations work. Registering a domain with https://app.ens.domains/ only cost $5 per year BUT you need to pay the Ethereum “gas” (i.e. pay for the energy required to perform the registration and get the transaction recorded on the Ethereum blockchain, as of this writing about $75).
Is it worth it? Hard to say at this time but if you’ve got the gas money 🙂 why not?