i have it. Since I have comfort access, it's mostly a cosmetic piece. The major downside is the screw sometimes comes loose and everything falls apart, so you need to check the screw and tighten it once in a while.
To answer your question, I tried to push the buttons through the cover, it's not very direct. If I need to push the buttons, I usually flip it out to push. Now the question is, do you really need this? Not really, but I don't drive my car everyday, and that key is in my bag and this sleeve prevents the key from getting all scratched up. It's very durable and I've had it for over 2 years now.