I haven't been keeping track of all the pet changes on the PTR right now, but the ones that affect me seem pretty interesting.
Wolves are getting their howl changed quite a bit:
-Furious Howl now only affects the hunter and her pet (currently bugged so only pet gets the buff?), but it now stacks with other AP buffs. It's about time, and I am just thrilled about it. :)
-Duration increased to 20 seconds from 10, but cooldown increased to 40 seconds. The AP amount looks like it has been increased to make up for this. I'm not too excited here, honestly--I liked having my buff up all the time. We'll have to see how it pans out, but mostly I think its just stupid. Having to time big shots to get the buff? Still not being able to trigger the buff manually because the cooldown will be short enough to put it on the pet GCD? Fail.
Hydras (and all other Tenacity pets) are getting some love, though--Thunderstomp will now be a Tenacity talent instead of for Gorillas only, so I won't feel bad about avoiding the buttscratching, banana-stealing nuisances. Sassy already stomps around quite well, I think she's been practicing.
One thing I haven't heard about is Bad Attitude, which seems to be bugged for me (no idea if it is on the PTR, this is on live). It's a 2-minute cooldown, so even with full points in Longevity it shouldn't be on the pet GCD, I think--but it's acting like it is, and I have to spam the crap out of it any time I want to use it, just like I used to with Roar of Recovery. It's way too long a cooldown to leave on autocast and hope it's up when I need it, though. Not happy about it. I'm thinking of taming a normal croc to test it out, but I'm not sure where to go with it after that. Maybe I should skim the o-boards first.