I'm not that sure about this barrier nerf whatever.
Played multi matches on elementalist and barrier looked the same. Cooldown wise, decay wise, damage absorb wise.
On AW CL still fill from 50% to 75% of my barrier (depend on crits mostly) and it still feels the same in combat.
If there was some nerf it was small, not "big" numbers for sure.
As for the katari. This guard is great really. MP lacks stats so it's hard to tell how much guard it is really per hit but for me, (promotios stats 21/21/21 with superior health belt and 16 cond from armor) it's 2 "bars" of guard per hit, so quite a lot.
It probably affects newb or those without high cunning. When I last played I had already reached 1/4( promoted - 10) and was trying to get 1/2 crit chance so my barrier would go from nothing to full sometimes. Whereas I noticed new players using spirit blade and could not manage to get barely any noticeable barrier. I just installed mostly to see what changed with the Katari, I wanted to play that class for the longest but just couldn't.
I tested barrier for aw lvl 9 perilous, I can solo
post patch. I was getting less barrier though, I would get 75-100% but was now getting 50-75% but then again I usually go to perilous at level 10+ so it could be 1 or 2 extra damage buffs missing. Anyhow, let me see how this Katari changed 
I thought I was going to dislike the door closing wave 5 but I find it ok, I'm confused. Maybe my team was just that good it didn't have all the preconceived flaws I thought it would with the change.
As for the Katari, the buff is not that significant but with a superb-Hok ring I didn't lose any significant health that I couldn't regain. This opens up new builds for the Katari, and the buff doesn't make the Katari the new AW. One good thing which I hope last, is that I was not the Lagtari, charge worked great and my position wasn't constantly reset which causes more downs than I can count.
Back to waiting for new content.