Surprised no one has posted these yet. Wowhead has them at Item sets - World of Warcraft. Here are the set bonuses:

Druid (resto and feral) - increases your movement speed by 15% while in Cat, Bear, or Travel form
Druid (moonkin) - reduces the cast time of your Entangling Roots by 0.15 seconds
Hunter - reduces the cooldown of your Multi-Shot ability by 1 second
Mage - reduces the cast time of your Polymorph by 0.15 seconds
Paladin (all sets) - reduces the cooldown of your HoJ by 10 seconds
Priest (all sets) - reduces the duration of the Weakened Soul effect of your Power Word: Shield by 2 seconds
Rogue - increases your maximum energy by 10
Shaman (elemental) - gives you a 70% chance to avoid interruption caused by damage while casting Lightning Bolt
Shaman (enhancement) - reduces the cooldown of your Stormstrike by 1 second
Shaman (resto) - reduces the cooldown of your Grounding Totem ability by 1.5 seconds
Warrior (all sets) - reduces the cooldown of your Intercept by 5 seconds
Warlock (all sets) - reduces the casting time of your Fear by 0.2 seconds

The bonus that really catches my interest is the Elemental Shaman one. It's going to completely remove one of the biggest liabilities of the class in 5s (you can't cast while you are being attacked). Pretty nuts. Perhaps they will change the shadow priest bonus from the current Weakened Soul garbage to something similar for Mind Flay.

Strange the blizzard nerfed their burst DPS potential with the LO change, but then added this to the gear. I am not sure what they are trying to do accomplish, balance-wise, with elemental shaman in PVP at this point.

Also strange that the moonkin bonus is the same as the mage one, except that the form of CC it is applied to is significantly less useful; one would think the cast time reduction should be increased in that case. (See warlock bonus)

Well, these boni are not just S3, but also S1 and S2, because all items even from different season are now belonging to the same set.

The new elemental one is really great. From one of the weakest (2% crit to shocks, lol) to a very strong one. Can't wait to test this one.

It's easy to see that they wanted to nerf the shaman's burst, but then compensate by buffing their damage output outside of that.

Shadow priests should probably get a different bonus than holy priests. The moonkin one seems pretty useless to me, you'd think they'd give that bonus to cyclone instead, a CC that actually is useful.

Its already on gloves.

What does that have to do with 4p set bonuses? They aren't mutually exclusive.

Then it becomes the same as saying mages should have an additional poly shortened cast time on their gloves. Stacking quicker CC casts just leads to more people wanting their CCs quickened. Asking for that for druids just leads to other classes also wanting it. I midly agree the roots buff is lame, but I think an additional cyclone buff would be a mistake.

Surprising how much difference there still is between classes. The hunter bonus is.. again, not really amazing compared to the warrior or rogue one for example.

Depends what side of the fence you're on. For example, the rogue bonus seems to be rather useless since the days of 120 energy double backstabbing seriously denting an opponents life are long gone.

The warrior set bonus blows all the rest out of the water, and while the hunter set bonus isn't useless, it's not really playing to a hunter's actual role in arenas. A 4 piece bonus related to trap duration/cooldown or viper sting effectiveness/cooldown would be much more reasonable.

I really don't understand why the warrior set bonus is such a huge chunk off the cooldown, while the others tend to be very minor comparatively. 5 seconds off a spell with a base 30 second cooldown (that is pretty much always 20 seconds talented) is a huge percentage, while 1 second off a 10 second cooldown ability isn't nearly as significant - especially given the relative impact of the two spells.

Apparently its too much to expect Blizzard to know how to play a perspective class in an arena setting beyond the 1600 bracket.

Good news, however, most of the dispel effects (cleanse, remove curse, etc) have been upped to 40 yards - same range as max range heal.