I am a little bit late to the party in terms of weighing in the heroic dungeon changes. Many other bloggers have made the point that they like hard things and don't want everything to get dumbed down to Wrath levels. At least one post says almost the same thing I'm about to say, but like everyone else on the internet, I assume I am a unique snowflake and have my own valuable take on things.
I don't want to go through the changes line by line the way Righteous Orbs did, since I think if you want that you can just read that post. I want to say a few general things about changes, though, and why I like the thrust of these changes in general.
It's important when a change comes to not get too caught up in how things are now. Changes are changes because there was a way it was before the change. If there isn't they are new things rather than changes. But we tend to get too caught up in how things were and don't pay enough attention to how things should have been in the first place. Changes that change things so that they are how they should have been in the first place are good changes, even if we kind of liked something about the bad state things were in.
Many of the "nerfs" to these encounters seem a lot more like bug fixes. While they may not always deal with literal bugs in the code, they are correcting what we may call bugs in the design.
First of all, there are many changes to the visual effects of boss abilities to make it easier to distinguish what they are doing. Being able to distinguish what the boss is actually doing does make encounters easier, but it is also how things should be in the first place. A boss that dropped invisible fires would be harder than a boss that dropped visible fires. A boss that dropped fires that appeared to have a radius of 4 yards but really had a radius of 10 yards would be harder than a boss who dropped fires that looked as big as they are. A boss that requires you to hit your "G" key (regardless of what you have it bound to) at 1:30 into the fight to avoid dying without giving any indication that this is what you had to do would be harder than a boss that did not have this requirement or that put up a raid warning telling you you had to do it. But in each case the former is a pretty bad way to make a boss hard1. If the boss is going to drop fire, the visual effect should line up with the game effect of the fire. If you want to make it harder, do so by making the fire do more damage, or giving me less time to get out of it, not by not letting me know where it is or what I am supposed to do.
Second there are changes to bosses that seemed overly sensitive to group composition. I agree with the principle but not the form of many of these changes. There should not be a boss that requires two beast CCs to beat, or one that requires interrupts more than once every 10 seconds, or one that requires two snare effects. Bosses should be beatable by a tank, a healer and three dps in ilvl 329 gear with good play.2 The specifics of how Beauty, Ashbury and Erudax were nerfed didn't deal with the issue appropriately, though. Beauty went from being nearly impossible with only one beast CC and fine with two to being fine with one beast CC and really, really easy with two. A better solution would be to make the pups a lot less threatening, give them less health, and make Beauty herself more powerful. Ashbury could have simply healed for less with Mend Rotten Flesh, perhaps 10% instead of 25% of his health. That way interrupts would have been good but not required. The Faceless Corruptors are now still pretty hard to deal with if they are not slowed but even easier if they are slowed. They should have had their movement reduced more dramatically and been given an immunity to, or at least a severe resistance to anything that would slow them. Maybe reduce the duration of slowing effects on them by 75% or 80%.
Third there are changes that don't really make the encounter easier, but people call them nerfs anyway. Foe Reaper 5000 does take a long time because you are down a dps. Making it a little shorter doesn't really make the fight much easier to master, just a little less boring after you have mastered it. Slabhide spending little time on the ground was a key factor in allowing us to beat him more than a minute and a half after our tank died. If he'd spent more time on the ground then shadow priest tanking would have been unsuccessful. Grand Vizier Ertan may have less health, but that's just to compensate for the fact that you'll actually have to pay attention to his mechanics now.
Of course the patch has undeniable nerfs in it, but I agree with most of them. Setesh seemed significantly harder than his compatriots on the second floor of the Halls of Origin for PuGs. A little more time to avoid Corborus and Ozruk's sudden death attacks is welcome as those are real PuG killers. A reduction in damage from the Naz'jar Tempest Witches sounds like a great idea, as does the reduction in damage from trash in Throne of the Tides.
And when looking at the "nerfs" it's important to notice that some bosses were made harder, and rightly so. Ptah, Asaad, Walden and Anraphet were all real pushovers - I doubt the changes to them will even go far enough towards making them harder, but we'll see.
So what don't I like? In addition to the specifics of the composition sensitive boss changes I mentioned above, there are a couple of boss nerfs that I simply don't understand. Specifically, I don't understand why Valiona was nerfed in the Drahga Shadowburner encounter. No one is supposed to be getting hit by that ability anyway, and the challenge in that encounter is dealing with adds properly, so the change makes little difference. I also don't see why Throngus' impale shouldn't still be a stun. I know people don't like their healer getting impaled, but if you play that fight right he just doesn't do that much damage. I really don't understand the Ozumat nerf in the Neptulon encounter either - but maybe it's just that Prayer of Healing is very good for that part of the fight.
There are also a few things that I find it hard to believe they didn't nerf. I feel comfortable calling Springvale the hardest boss in any heroic, and I think he could stand to have his melee damage reduced, even if only a little. Also, they reduced the damage of Gilgoblin Hunter's Poisoned Spear attack "slightly." Rather than "slightly" that should probably say, "by half," and there should be a similar note regarding the aquamages and their tsunami. Having a pack with eight enemies, each of which has a 40k attack is a little bit much. Generally how that pull goes is the tank pops a cooldown while running in, we start AoEing and just before we kill them four aquamages tsunami at once killing the tank and any melee, then we clean them up. Chained tanking CDs for the duration shouldn't be the norm for trash pulls, and, more importantly, should be sufficient to avoid one-shots if you can actually pull it off.
I also wouldn't have minded seeing a few other changes:
Corla in BRC should have her haste aura removed and her attack speed and damage increased so that she does roughly double the damage she does now in the end. This would make the fight easier when her friends evolve and not trivial if they don't.
Halls of Origination
Veil of Sky should be made more powerful and undispelable while Astral Rain should be reduced if it is left for the third ability on Isiset - the damage seems fine at both the first and second thirds of the fight, but appears to be multiplied by about 10 if you leave it as her last ability. The rain does nearly twice as much, hits all five people instead of just two, and lasts seemingly forever. Simply affecting everyone with no damage or duration increase would have been fine.
Baron Silverlane could have used a buff of some kind. Lord Godfrey should have the damage of his cursed bullets dot reduced and his other damage increased to make the fight less dependent on whether you have a curse remover. I don't mean that a curse remover shouldn't be helpful, but he should be beatable in reasonable gear without one in the group.
Throne of the Tides
Mindbender Ghur'sha should make your allies more threatening when he controls them, take control more often, and do something when he's flying around by himself.
1. I could actually imagine invisible fires having a place in some boss fight at some time, but it doesn't seem likely, and the other two examples are right out.
2. Giving paladins tanks an interrupt will also help with this.