I can't say I'm the biggest L4D2 fan, but after my test to improve the TF2 config I went after this game.
First of all whoever at Valve put together the dev build probably didn't even play multiplayer, or single player. You can't seem to exit out of the Message of the Day since fire =/= left mouse, nor can you change teams. Grenades are not a touch pad option for whatever reason even though they left one button free in the 7 slot touch menu, and you can't skip the credits after a campaign since the jump command =/= the space bar. Also I don't know about some people but even if you don't have a ton of gear to switch through I live and die by next/previous weapons.
My touch menu is
Primary / Secondary / Grenade
Pills / First Aid / Screenshot
Orders / Q+A / Team
You could probably change it to a 4 button touch menu without the weapon switching. Since this setup allows you to switch back and forth between items.
Getting the text commands (Orders and Q+A) to work also required changing the right pad from the Camera ingame binding to the legacy mouse binding. Which goes to show that sometimes native support commands aren't always better. I really wanted the commands in when I can't always use mic, the only sacrifice I had to make was putting yes/no on buttons instead. This is the first build I really played around with the triggers as well to get Rifle aiming right, glad I did because it plays really well.
Also here is the setup for those who might care:
http://pastebin.com/A3qP4xJg