FWIW, I've long wanted to start using more reactive programing and so have dabbled with RXSwift and ReactiveSwift. However I've never been able to get past dabbling due to difficulties integrating it into existing projects. If you can go all-in, it seems wonderful! However the on-boarding process is far from simple due to the specialized verbiage and APIs and (for me) it became an all-or-nothing situation.
I had a lot of difficulty adding it to existing codebases without completely re-architecting how they worked and ending up wanting/needing to rewrite the entire thing. Accessing the power it provides seems to inevitably result in a draconian takeover of your codebase.
Combine, at least at first/second glance, seems a bit more constrained and focussed. I'm optimistic it will be easier to add to existing/new portions of a codebase and allow for gradual transformation, rather than a hostile takeover
Side note: I'm guessing it's supposed to be Combine, but does anyone else keep pronouncing it COM-bine in their head? I can't stop