I switched mine to the OEM touchscreen because I got it for so cheap. Between the OEM HU, having it unlocked, nav antenna, and speed sensor harness, I was under the cost of what the adapter harness and module(s) required for an aftermarket HU alone would've been. Plus the rear seat controls are still functional so I have no non-working OEM equipment.
The steering wheel controls work just like pressing a button on the HU itself. They have symbols and are pretty intuitive. About the only ones I use are the volume and "up" and "down" buttons. I can't say I noticed any difference in sound quality with the swap. I'd guess they have the same output circuits and the only difference is how you adjust the settings (knobs/buttons versus touchscreen). Looking back, I wish I would've saved up more cash and went aftermarket. The rear seat controls would've been disabled, but nobody uses them anyway. Every other OEM function can be retained with the proper adapter module(s). You'll have a better screen, better sound shaping capabilities, easier expansion potential, MUCH better nav, Bluetooth calling AND streaming capabilities, and so much more.