Playing a Paladin, a Death Knight, a Warrior, and most recently a Druid since the beginning of Cataclysm, the one class I saw with a problem and kind of looked disappointed when I saw the patch notes was Feral Druids. I love the feel of cat form and bear form, and I feel that they were both (for the most part), fair. Damage output may have been high, but hey, that's tweakable.
Now, I've been decent in arenas; kind-of-sort-of on and off, if you will, and I noticed that the Berserk fear immunity and the Shapeshift Root Cancellation were two primary components in staying alive against a decent amount of teams, particularly Frost Mage/Demo Lock. An excess of roots, fears, and stuns; too many for a single PvP trinket. I had gotten good at root cancellation and survivability, using cds when necessary. However, even that was not enough against some of these teams; it was like, if you were caught root cancelling or something of the like, you were instant-killed by massive damage output by the other team.
After reading the patch notes and having a disapproving look on my face at the removal of the fear immunity (which could have been lowered to an 8-second PvP duration, as they did with near everything since it's instanced and, with the time it took for the patch to be ready, they could have done it to appease other classes) and the removal of the Feral root cancellation (which could have been implemented into the talent Improved Feral Charge, where it removes roots on use of Feral Charge, [which again, albeit a nerf, it is not a complete removal and we could have dealt with it]), I died on the inside a bit. I looked at my Druid, thought for a moment, and decided that I was just going to PvE because Boomkin PvP is just not my cup o' tea, and the same with Resto PvP, however fun it may be.
Looking at my other classes, I realized something that Blizzard relatively flawed themselves in: the root cancellations of Death Knights, Warriors, and Paladins were on cooldowns, and even though the Feral Druids root cancellations were not, they could have easily fixed that issue to make Feral Druids more comparable on the scale with other melee classes. Paladins use Hand of Freedom, resting on not a large cooldown, but not a small one either; Warriors can use Bladestorm to escape roots - and yes, I realize that this is nearly a 3 minute cooldown - there are some aspects in which some don't realize that it is a major damage dealer as well as an immunity to most forms of crowd control; Death Knights can use well-timed Anti-Magic Shells to prevent roots and other effects, and similarly can use Icebound Fortitude to protect against stuns (and only stuns). [Note: keep in consideration of the PvP trinket as well.]
While a free trinket slot may have been added to Feral Druids where other classes were using the PvP trinket (in some random scenario that may occur), do realize that now all Feral Druids have to rely on is that sole PvP trinket, in which other melee classes didn't. It was a nerf that was poorly placed (example: put the root cancellation into a talent where the ability has a relatively decent cooldown and make it last ~4-5 seconds? [Comparing to the Warrior's Bladestorm here]), and devastating in conjunction with the removal of the fear aspect of Berserk, which was also poorly placed (~8 second PvP duration? PvP zones are instanced - I mean, it's not too hard of a mechanic to implement seeing as all they'd have to do is use it as a buff rather than a debuff which is the duration most crowd controls have in PvP anyways).
All in all, easy fixes were and are still available; but as of right now in the current situation, Feral PvP is really going to be hurt by these nerfs.