It took you 10 seconds to download 15gb? Lol. I'm sure you mean the patch after the disk installation?
My game took about 10minutes to install (On an SSD though). And I got it on time in the end, so happy days.
Diablo 3 is very very fun. Playing Nightmare through now, level 42 or so.
I bought the digital version and maybe I'm just remembering wrong but it seems like it didn't take any time at all. Installing the game did take a while though