I actually watched and observed the whole hour of WoE.
From what I saw, players were having a hard time with the guardians. I also noticed that guardians have some sort of skill that reveals cloaked people, as most assassins I saw cloaked was suddenly hit by the guardians, and they do about 5K damage on some people with I assume, 195 Aspd.
And also, some people can't hit the guardians, possibly because their flee rate is high, and I watched someone fight a guardian doing like 32767 damage all the time, and not killing the guardian.
Two guardians on an individual would really be a challenge.
In my honest opinion, the guardian buffs were good, but it would be better if they had a downgrade of some sort since they are overpowered.
Overall though, they really spiced up WoE. :)