More clicking and more updating. It's frustrating to have to go through windows to get to what I want. Not strictly relevant to WoW, as this is the WoW forums and not the Hearthstone forums, but:
I want to play Hearthstone; have to boot the launcher, launcher wants to patch, close launcher, reboot launcher, hearthstone needs to patch, wait until it's done, launch hearthstone. That's, what, 7 steps before I've even opened Hearthstone.
Compared to, say, ye olde starcraft;
Open game, sign into battlenet. There's an update, starts download. When the download's done, close starcraft, restart starcraft. 4 steps.
On top of that, 50% of hearthstone's development and the jibberjabber from the devs about Hearthstone has been that you can "get right in and play a game". When you get stonewalled by two sets of patches, you're waiting for anywhere between 5 minutes and an hour. That might seem trivial, but it shoots that idea right in the face.