Malfiore
Keeping this fairly succinct. I play an all-dex elf thief and don't multi-box; I run either solo or with my wife's character (also an all-dex elf thief…)
Forgotten Dungeon
The randomisation is a great concept, especially as there's a wide range of minotaur classes… but it ends up feeling repetitive anyway, save for the handful of captured aegiscians. I'd like to see more creature types (for example, wolves/fenris as battle hounds). Running it for loot is a pain due to the number of necessary fights, and reaching Minos Prime feels like it takes one corridor longer than necessary.
Thieves Hole
The classic and quickly abandoned stepping-stone dungeon. I like the new bosses. I think a few caster thieves would make it less predictable.
Festering Hate Pool
The tweak to the bat fight was a good idea. FHP is fun because of the variety of fights and its peculiar disjointed layout. I'd like to see a proper boss fight somewhere (maybe an enormous medusa?), and perhaps a few high-level fights dropped into the wings to keep the dungeon relevant for longer.
Snake Pit
Even more repetitious than Forgotten Dungeon, due to snakes being such plain enemies. The peculiar Keeper "boss" really deserves to be boosted (and maybe accompanied by hefty caster creatures: dark faeries, ghosts?) At the same time, the earth elemental encounters should either be only one elemental, or they should lose some spell damage/Crushing Boulder. These fights are absurd roadblocks. Also, the loot here is awful.
Fuloran's Abode
Fuloran is easy to run rings around, and there's so rarely any good loot here… overall, feels irrelevant.
Tulor's
Running the gauntlet gets a bit old, and it would be nice to have an optional early side-fight, quite challenging, that allows the player to skip some rooms ahead. (Perhaps at the cost of the KK chests.) Some enjoyable fights toward the end, with the mixed fury/devil/kilrog/KK groups. Tulor himself casts too much CC–without myst immunity, it becomes obnoxious. Otherwise one of the more engaging dungeons.
Imp Haven
Either a peculiar mish-mash low level dungeon or a bland run from one easy King Kilrog fight to another. Needs a revamp.
The Barracks
Decently varied. A proper revamp might put a boss-type before the two chests at the end.
The Foundry
I've only run this once, through the evil wing. The early Harlequin is a show-stopper for solo characters and those without myst spells; the rest of the encounters are much easier (assuming one can handle dwarves) until the Blacksmith, who like Tulor can be obnoxious due to the player's lack of myst immunity. I'm not sure the Harlequin is placed correctly - it would be good for a solo character or weaker group to be allowed further before calling it.
Daemon Home
A vile frustrating dungeon, with only a single deserving encounter (Ezelberoth) accessed through three meandering wings of low-level encounters. Needs a total rework.
Undead Stronghold
I really like the new USH - not much else to say about it. Mother could be given some spell-casting ability, and perhaps shifting, to make her a more interesting adversity.
Others
I've not run a few dungeons on the new server (for example Anvil, Holy Caves). Among the rest, some dungeons (like the Labyrinth) are wandering, dull, and encounterless, and need a serious overhaul; others (like Warrior's Abode or Fenris Cave) just need better progression and a boss fight of sorts. But these have all been pretty irrelevant to my levelling process, as I've spent more of my time in the places above.
curious to hear more thoughts.