I do use it, but it's worth double checking sources. These are some problems I uncovered when looking, if you're interested.

https://medium.com/bouncin-and-behavin-blogs/if-you-use-wikimedia-commons-check-the-source-of-the-images-some-are-not-free-to-use-29ccf059a0b4

https://medium.com/writers-blokke/i-found-the-perfect-creative-commons-photo-then-spotted-a-legal-problem-bd0c0d83e2b3