For what to work?
If you're at CB and see it available, get it. I don't see any downsides.
Pre-fund it.
Spend $10 somewhere, get 0.40 back in crypto.
Spend $2,000, get $80 back in crypto. etc.
Last week made a spreadsheet of everything I'm using my credit cards and debit cards for and moved about 90% of it over to the Coinbase Card. Just last week, door dash, door dash, amazon, netflix, hosting for sites, spotify. Just adds up, even the lowest amounts. I figure if you're spending money, might as well get the highest percentage you can get back. Now it's crypto so it can go up or down but imagine the crypto you get goes 2x, now you're getting 8% back. Can always cash it out whenever you want or convert to a crypto you might like better.
I was hesitant at first because I didn't want to start getting cards from different exchanges but now I wish I would have done it sooner. No issues, it's really smooth with that card at CB.
Current rewards. You can choose whichever one you want, you can rotate them etc. I remember being a few more coins so what's available may change, the percentage may change but so far the 4% has been available.
Stellar - 4%
The Graph - 4%
Bitcoin - 2%
Cosmos - 2%
ETH - 1%