My gripe is the portal hubs. Org is the only city with the portal hub so if we’re looking to get to Pandaria or Icecrown or Caverns of Time we’ve got to go through Orgrimmar.
The portal room is indoors so it’s not like we can mount up, and if you get infected in the portal room you can’t portal out because you’ll take the infection with you, so you need to run out to the healer then wait for the invasion to be over before going back into the portal room.
Additionally, unlike the previous invasion, the infection doesn’t seem to be typed (not a Disease), so I assume even players with Cure Disease spells cannot cleanse themselves; the NPC is the only way to remove it. And there isn’t an NPC on the other side of the portals (which there should be).
I have no objection to the event in general, but these things make travel even more of an irritant and a waste of time, and Blizzard has already been making travel a pain in the neck enough already.