You've played the computer version, you've played the console version, and now you'll be able to play the handheld version too. "Now" means this Thursday when The Walking Dead will hit iOS, with the first episode pricing in at just under $5. You can pick up the additional four episodes for $15 or just keep paying for each game individually if you like wasting money.
Check out Telltale's blog for some screenshots. Looks like the touch interface is nicely thought out.