Is my 2017 Oyster card still usable.

It should be fine. Just tap it on one of the ticket machines and check. BTW you can also use many contactless credit cards and smartphones to pay too.

I was just in London in November and my Oyster card from 2015 still worked and it still had funds on it. I personally prefer the Oyster card vs using my contactless on The Tube because I don't want my credit card or phone out in a crowded Tube station, and I don't like a lot of small charges on my credit card. Have fun! London is amazing!

Mine’s even older, and still worked this past year. That piece of plastic is built to last.

Ditto. Got mine in 2009 or so and it worked last March.

My card is from 2011, works perfectly, and last year I bought it a new holder from the London Museum of Transport.

Thanks everyone. Sounds like our cards should work just fine.