The power and volume buttons can press very smoothly despite envelope, just as would be the case if you use any envelope. The feel of the device is determined by the envelope even better, because the surface has more grip and the iPhone is thus significantly more manageable! Just the best.
Only criticism: The shell sits a bit loose, so they are in the pocket also schonmal separates from the corners. Therefore only 4 stars. Still, I can absolutely recommend the sleeve for the price.