1: "It's a trash fight!"
Personally, I don't subscribe to this idea, that just because you're not crossing swords with your foe directly makes the encounter dull. I firmly believe that the finest end of tier boss this game has produced was Yogg-Saron, a fight which consisted of me doing nothing but tanking minions and tentacles. At the same time, having a static boss that can't change position does severely limit the perception of freedom in an encounter, and I can understand that idea.
2: "It's so looooooooong..."
Yeah, fifteen minute fights can be a pain in the ass. They can also be amazingly epic. Kil'jaeden, Yogg-Saron, Lich King, Nefarian in both incarnations, were all amazing encounters that took a long time to kill, even when they were on farm. It sucks when you wipe late in an attempt and you have to start all over, and it's a bit of a kick in the crotch when you look at the clock and realize that despite whipping your raid for quick turnover between wipes, you've spent an hour and only gotten four attempts in. I don't think that this is something that makes a fight bad in and of itself, but it really exacerbates other factors, such as...
3: "Rinse, repeat, rinse, repeat, rinse, repeat, rinse, wipe"
I understand what Blizzard was trying to accomplish here. They wanted to make a dynamic encounter that evoked shades of Yogg-Saron with the four godlike beings assisting you at varying levels. This is what they wound up with: a fight where nothing matters until ten minutes into the fight. The encounter is completely trivial until the final platform. A lot of the mechanics are solid, CD coordination checks, positioning checks, AoE strength checks, and single target coordination checks. They're all good, but for most of the fight, they're completely trivial. It amounts to the Kael'thas or Tirion RP before the fights in BC and Wrath, it's cool the first time, but God it gets old fast, and I can't even go get a drink during this stuff.
4: "Thrall Hates Me."
This is the one that really irks me. Blizzard dropped the ball on the coding for the wind tunnels on this encounter, and often enough to be a noticeable problem, Thrall will just drop players while making the transition to Kalecgos' platform, which also tends to be the one that groups go to last. While it's bad when this happens to a DPS, when it happens to a healer or tank, it's pretty much guaranteed to be a wipe. You can't battle rez them, you can't prevent it, you can only lament the ten minutes of your life you'll never get back. It's happened to me with two different guilds, and at least seven different players. I'm not the only one who's seen this problem. Honestly, Blizz, what were you thinking here? Besides, Green Jesus is supposed to be the Aspect of Earth. Just have him make a goddamn bridge. A nice solid bridge of stone that if a player falls off, its their own damn fault. On an entertaining side note, if you open a ticket citing this glitch as an example of Horde Favoritism, a GM will answer it in three minutes flat.
While Spine of Deathwing doesn't have near as much hate as Madness on normal mode, it still suffers from the same flaw of repetition.
So, how would I have fixed this problem, making Deathwing into a fight worthy of the end of an expansion?
1: Combine both encounters into a single fight.
No break to loot in between Spine and Madness. You pry the armor plate loose, Thrall takes his shot, everyone lands at the Maelstrom, DW erupts out, and you go right back to carving him up. Recovery time is for wimps, tempo is everything. This also sows the seeds for a badass RP moment. The finest RP moments in raids are always the mid fight ones, not the ones that get handed to you just for pulling. I think part of it is because when they occur midfight, they have a built in tempo that prevents them from taking too long, and I think that having them occur mid fight keeps you from focusing too hard on them. It's like a Monet painting. It looks beautiful from a distance, but the closer you examine it, the more it looks like just a few colored blobs. For me, the coolest moment in the game is the phase two transition on Yogg-Saron, where Sara goes into a brief monologue, her voice warps into Yogg's, and Yogg emerges from the ooze laughing maniacally. Kil'Jaeden's eruption from the Sunwell is up there too. I think Deathwing clawing his way out of the Maelstrom could rival that if they didn't give us the nonchalant period of bitching over which trinket dropped before hand.
2: Scale back the repetition, scale up the individual mechanics.
Instead of three plates on Spine and four islands on Madness, I'd go one plate on the spine, leading into one island on Madness, which automatically breaks into phase two when you've cleared the Limb Tentacle. Increase the health on the Burning Tendon, so you force the group to pop two amalgams to proceed to the next phase, and once the tendons goes, Thrall blasts Deathwing, and you leap off right before he hits the Maelstrom. Token "Nothing could survive that..." from Green Jesus right before Deathwing rears up out of the Maelstrom and strikes down all four aspects, forcing the team to break his grip upon the island, and the Aspects. Increase the health on the Tentacle to force most groups to go through 3-4 impales, rather than 1-2, and it would make the tank swaps more interesting, as the tentacle will probable still be up when the Bloods come out. Extend the duration on Cataclysm by 50% to compensate for the decreased uptime and the lack of the spellweave buff when dropping blistering tendrils. Phase two remains pretty much unchanged, aside from the fact that it's now actually phase three.
I think that these changes would aleviate a lot of the major complaints about Deathwing. It would shorten the duration of the fight, although not dramatically. It would decrease the repetition, and it would completely remove the RNG Aspect of Derp deaths that infuriate people.