Gave this a try a few weeks ago (for CLion with Jetbrains Client, IntelliJ for Java might be further of course) and felt it was still quite lacking. Loads of features weren't there yet. Of the top of my head: no way to use my customized keymap, no git blame annotations, fundamental navigation shortcuts missing (jump back, navigate via file structure), no way to attach the debugger to a process, ...

I went back to remote controlling the full-featured IDE via Projector, their earlier approach too remote development. That works extremely well for what it is. Probably the richer Gateway client will catch up in a while, but not quite yet.