They aren’t as natural. E. g. you have to swipe the same direction to open or close the window overview, whereas with GNOME the animation actually follows the direction your fingers are swiping. But they at least reliably trigger the action you want to execute.
Since Plasma doesn’t have dynamic workspaces, I use it completely differently than GNOME anyways. E. g. I don’t make use of workspaces and use minimise instead. Therefore touchpad gestures on Plasma are much less relevant to me than on GNOME at the moment.