It's crap compared to my Xbox One/Windows streaming (this is probably the best experience of the three) and my Wii U remote play which is severely limited by the wireless range of the console itself (why it can't do this over the wifi network rather than it's own hotspot is beyond me).
Even with both my PS4 and my Win10 laptop connected on LAN cables there are artefacts, delays in control inputs, etc... this applies to both the newer Remote Play as well as on Vita (connected via wifi obviously). It's playable for slower games but even then, the input lag can be a pain making it hard to play.