I ran The Sunken Temple of Qarn last night, and holy crap does the difficulty increase in that dungeon! The group I was in was made of of relatively new players like myself. Our tank was familiar with the dungeon, but all in all I think if we had been doing one of the lower level dungeons we would have been fine.
I seriously felt like I was running a raid last night. First of all, trash mobs in this dungeon are ridiculous. They weren't particularly hard, but they seem to have way more health than trash mobs in previous dungeons. However, there are some trash encounters where you have to lure special stone face statue mobs onto pressure plates in order to open doors that let you keep going through the dungeon. If you don't kill the statue on the pressure plate it will instantly revive itself with full health.
The first boss starts out like it is going to be a tank-n-spank, but then adds spawn in that can 1-shot players unless you kite them around. And then at 50% the boss starts doing room-wide abilities that debuff people with Doom (a classic Final Fantasy status that does nothing to the player until it counts down to zero and then you instantly die). In order to get Doom off you have to stand on special tiles on the floor, which also means you can't remove Doom and kite adds at the same time. We wiped on him about 4 times.
The second boss is a stone golem that is all about not standing in the way of his abilities. His aggro is kind of crazy, so he will often peel off and throw long-range abilities at other players. He will also do a room-wide stomp that damages everyone and sometimes he will chase a random player and stun them. He doesn't take much damage, but there is a soulstone that emerges that dps needs to burn down asap. Once the soulstone is down the boss will be stunned for several seconds in which he will take massive damage. The healer really needs to be on their toes as you have to keep moving. My group had a problem with a healer that did fine when she didn't have to move, but she wasn't very good at paying attention to imminent danger.
The last boss is insane for a non-endgame boss. It's a 4-phase fight. The first 25% of his health he will summon in more of those stone face statues. There are 3 plates on the ground where you have to lure the statue to the plate and kill it so it will despawn. If you don't kill it on the plate it will revive, and meanwhile more statues are spawning in.
The next 25% of its health it continues spawning statues, but now Mythril verges will spawn. The verges need to be destroyed immediately. They don't have much health, but they will shoot a laser that can 1-shot players. If left up too long the verges will start to turn and sweep the laser across the room.
At 50% the boss continues doing all previous abilities, but now starts spawning a different kind of verge where the dps needs to stand on a special square in front of it and dps it down. Meanwhile, the dps destroying the new verges are unable to be healed until the verge is destroyed.
The last 25% of its health it just increases the difficulty of everything by spawning more of everything.
It was a very exhausting dungeon run. I just went to bed after that. I imagine that once we get enough SN folks up to that dungeon then coordinating through TS will make things go a lot smoother, but be ready to get into a raid state of mind because the milk run dungeons of the lower levels come to a screeching halt.