All of the "What this means:" sections will refer to Feral specifically, not necessarily the class as a whole.
Cyclone duration has been reduced to 5 seconds, down from 6.
What this means: Fairly simple. Cyclone has received a slight nerf to keep it from being OP when used by Balance and Restoration Druids in arena. This spell has a 1.7 second cast time, which of course can be reduced by haste. Unfortunately for Ferals, we don't stack haste, thus our hard cast for this CC ability can be rather brutal. This nerf, while intended to balance out the OPness with the Birds and the Trees (since they don't have to shift to cast this spell), has in fact hurt Feral CC capabilities in arena/BGs quite a bit.
Pros: Attempts at CC balance have been made. Rejoice for this change when going up against another Druid.
Cons: The hard cast time makes this easily interruptable (no change really), the extra time it takes to shift forms for a Feral makes this form of CC tedious at best, and the reduced time simply gives a Feral even less time to DPS the non-CC'd target. The change makes Ferals who are trying to CC things cry inside.
Efflorescence has a new spell effect.
Lifebloom's bloom effect has been reduced by 20%.
What this means: Less extra heals whenever Lifebloom either finishes or is dispelled.
Pros: Less healing to have to worry about on opponent Druids in PvP.
Cons: Less self healing for your furry butt in PvP and soloing situations.
Prowl has a new icon.
What this means: We haz a shiny new button!
Stampeding Roar's duration has been increased to 8 seconds, up from 6. The movement speed effect has been increased to 60%, up from 40%.
What this means: Stampeding Roar is getting a slight buff. Longer duration + increased speed effect = win. This is great for a Druid and his/her team in a BG/arena as well as great for a raiding team who need to move lickity split.
Pros: The Druid and their team can now move faster for a longer period of time.
Cons: Opponent Druids are going to be a pain to catch in PvP.
Swipe (Bear) cooldown has been reduced to 3 seconds, down from 6.
What this means: Swipe is getting a slight buff via a reduced cooldown wait. My dear chubby friends, you should be able to have a bit of an easier time with AoE threat now.
Pros: More usage of Swipe = more AoE threat.
Cons: Still not quite as fun as the Swipe spam of Wrath.
Druids now innately have 100% pushback protection from damage while channeling Tranquility.
What this means: While a Feral's Tranquility spell isn't all that strong to begin with, at least we will now be able to make full use of this spell's duration.
Pros: More up time of an AoE healing spell.
Cons: More up time of an AoE healing spell of opponents in PvP.
Starsurge damage has been reduced by 20%.
Solar Beam is now more responsive when enemies move into or out of it.
What this means: Saz now has the Pokemon theme song stuck in her head.
Feral Swiftness now also causes Dash and Stampeding Roar to have a 50/100% chance to instantly remove all movement impairing effects from the affected targets when used.
What this means: Feral Druids once again have a way to efficiently break CC. While it's not nearly as effective as Shape-Shifting was, it's much better than nothing.
Pros: We once again have a way to break out of CC effects in PvP that isn't trinket related.
Cons: It's attached to our two movement speed increase abilities. Essentially we're popping two cooldowns at once to get out of a CC'd situation, and the speed increase may not be used at the most opportune moment because of this.
Gift of Nature (passive) also reduces Tranquility's cooldown by 2.5/5 minutes.
Efflorescence has been redesigned. It creates a healing zone at the feet of a Swiftmend target, but this healing zone now restores health equal to 4/8/12% of the amount healed by Swiftmend to the three most injured targets within 8 yards, every 1 second for 7 seconds. This periodic effect now also benefits from spell haste, but the individual ticks cannot be critical effects. In addition, Living Seed is no longer a prerequisite talent for Efflorescence.
Malfurion's Gift now reduces the cooldown of Tranquility by 2.5/5 minutes.
Glyph of Rake is now Glyph of Pounce, which increases the range of Pounce by 3 yards.
What it means: This is fairly straight forward. Glyph of Rake got the can and instead we now have Glyph of Pounce.
Pros: You have an extra 3 yards in which you can use Pounce from. Great for getting those opponents in PvP with.
Cons: The enemies are gonna getchya getchya! Maybe.
Druid Bug Fixes
The troll druid models for Flight Form and Swift Flight Form has slimmed down to be more in scale with other druid flight forms.
What this means: Trolls are now not quite so fat in their Flight Forms.
Pros: You no longer look gigantic.
Cons: You can't as easily dwarf Tauren birds.
Edit: New PTR 4.1 Notes
Swipe damage has been doubled.
What this means: more AoE damage for cat DPS, more AoE threat for bear tanks.
Pros: More damage output as a DPS/more damage output & threat as a tank. This is a pretty positive change.
Cons: None that I can think of right this minute.
Berserk is no longer on the global cooldown.
What this means: No longer will you have to incorporate Berserk into the feral "rotation" for either cat DPS or bear tanking. You may use it when you need it, regardless of where your GCD is at.
Pros: As stated above, you may now use Berserk when you need it. No longer must it be used in a "rotation," but instead it may be used at the most opportune and convenient moment.
This entry has been posted on both World of Saz and on Saz's alternative blog, Feral Spirit. You can find Feral Spirit on the Learn to Raid website.