The free geo information in the header alone is already worth it for us so we save money on purchasing a separate ip db but also don't waste time for the separate db call looking up the location.
I was very disappointed by their kv store latency and that d1 does not replicate yet. So we ended up comparing a poor man solution in just providing the json at a http endpoint on our webserver vs. quite a few global kv providers.
We set up a promise race and did thourough global tests. Doing the http request beat the global kv store providers by far, even if they have a pop in syd, the cloudflare http request to europe or the us was still faster. We are using Argo though, this might have helped as well.