They suck! I use an SL88 for touring because I can lift them. As a weighted controller, it’s quite nice but as a control surface (including pitch bend and mod)” it’s useless
Edit: just to be clear, by they, I’m referring specifically about the use of a joystick rather than actual wheels which I’m used to from instruments like the Minimoog. So that’s my personal opinion as a musician 
I wish the SL88 had regular wheels and even a few sliders.