Last time I looked at GraphQL it was only a time-saver if you could rely on significant amounts of automagic for the GraphQL->DB Query step. So if your use case & stack allow for that, yeah, maybe it'll save you significant time.
Its main effect is to move app logic query writing to the frontend, in something that's not SQL, which some folks seem to really like. But it's still got to get turned into whatever your data sources actually speak at some point, just like REST or anything else. If there's nothing magically doing that for you or if the magic turns out to suck, you'll be doing it manually.
[EDIT] to make it more clear, here are your possibilities:
1) a. GraphQL queries -> b. Queries for one or more kinds of datastore
2) a. REST requests -> b. Queries for one or more kinds of datastore
You shift choices about how to query kinda forward in 1, but that means you need a very general and flexible GraphQL query handler to make step 2 happen, and if that doesn't exist or is insufficient you have to write it. That is, obviously, more work than 2, in which 2b is where the choices you'd make in 1a happen, so that layer doesn't need to be as flexible.
TL;DR the apparent flexibility and responsibility-shifting of GraphQL isn't free and is in fact quite expensive (and, if I may, risky)... unless it is free because someone's already done the work, for your particular use case and stack.
Its main effect is to move app logic query writing to the frontend, in something that's not SQL, which some folks seem to really like. But it's still got to get turned into whatever your data sources actually speak at some point, just like REST or anything else. If there's nothing magically doing that for you or if the magic turns out to suck, you'll be doing it manually.
[EDIT] to make it more clear, here are your possibilities:
1) a. GraphQL queries -> b. Queries for one or more kinds of datastore
2) a. REST requests -> b. Queries for one or more kinds of datastore
You shift choices about how to query kinda forward in 1, but that means you need a very general and flexible GraphQL query handler to make step 2 happen, and if that doesn't exist or is insufficient you have to write it. That is, obviously, more work than 2, in which 2b is where the choices you'd make in 1a happen, so that layer doesn't need to be as flexible.
TL;DR the apparent flexibility and responsibility-shifting of GraphQL isn't free and is in fact quite expensive (and, if I may, risky)... unless it is free because someone's already done the work, for your particular use case and stack.