You had a problem with it? I haven't tried Diablo 3 specifically, but I find in most modern distribution platforms like Steam (or similar utilities from Blizzard) you just buy, click, walk away for 2 hours, and when you come back the game is installed and ready to play. It couldn't be easier to install native apps! -- when every thing works correctly.
One particular thing I noticed about Diablo is that it was playable long before it actually finished downloading. Most of the maps, video and artwork was downloaded as I played the first few levels. Pretty cool.
In exactly what way is this question a follow-on from the parent comment? The statement was, to paraphrase: "Purchasing and installing native applications can still suck, even with '2013 distribution'." IOW, all that's been saved in 20-odd years is the drive to the retail store, the drudgery of swapping floppies and (usually) the task of manually configuring a memory manager. We're far from an instant-on, pay-and-play world for native apps (and in some cases you still need to be connected to get moment-by-moment permission to run the app you "purchased"—the internet as dongle).