SPOILERS AHOY!
(but, hey... you're reading a thread about an adventure. What do you expect?)
Assault on Nightwyrm Fortress is broken into the following sections. The adventure is heavy on combat, light on role-play (alas!), but has a little problem solving and exploration to relieve the monotony. I'm going to try and give some preparatory notes to help you prepare to run it!
Introduction
Most of the roleplaying elements of the game occur here. The group meet with the cleric who can't raise the hero, the hero's father, and the odd friend-of-the-hero, Moyshanna. Oh, and they get attacked by Orcus's minions...
Orcus?
Yes, this is Orcus punishing the group for their actions in H1 and P2. Orcus isn't directly involved in the rest of the adventure (though what is learnt in it is important for the epic adventures). You can add more roleplaying/informative speak from the wight to press home this point: Orcus hates the PCs, and wants them dead. If the PCs take advantage of this to ask why Orcus won't let the paladin be raised, something along the lines of "it is nothing to do with me!" might help.

(In fact, if I recall the next few adventures correctly, he's lying: the Shadow Dragon is his unwitting pawn, but don't give it away early).
Sir Halumoor and Beldan?
Relatively inconsequential... except, of course, they're the spur that gets the adventure going. Getting the PCs feeling sorry for them would be a great start, although - for one-use NPCs - it's going to be hard to fully engage the players unless you've got one who's soft-hearted. It'd be better if they were
known NPCs.
Moyshanna?
Oh, if only she had a personality rather than "is mysterious!" She's really worth building up (and starting a relationship with the PCs). I wasn't able to do it, but I really have trouble running NPCs who travel with the PCs. She's walking plot exposition as well: directing the PCs to learn there's something wrong with the Shadowfell where souls linger for a time before going to their final resting places. As a Shadar-Kai, native to the Shadowfell, she understands these things, as should any PCs well-versed in Religion. As noted in my previous post, her stats suck for accompanying the PCs; if you can, restat her as a Companion from DMG2.
The Gloomdeeps
The first part of the dungeon delve, there are actually only two encounters here: most happens once they reach the Tomb of Sartine. What's really good about this section is the descriptive text in Adventure Book One that describes what the PCs can find in the caverns. Play to this and the strangeness of the Underdark (even if the PCs have only just returned from there in P2!)
The Tomb of Sartine
Did you know you can make the tomb entirely from Dungeon Tiles? Cool, huh? At least it would be, if I could be bothered finding the right tiles and taking them to the session. (I didn't bother in the end, just drawing the thing on my flipmat).
It's a depressingly linear dungeon, but at least it's short: only five combat encounters. What is *good* about the dungeon is - once again - the descriptive text in the first Adventure Book. This is a pretty evocative place. Run with it. I really like the burnt silhouette in T3.
Interestingly, the major artifact the group can find here - the Skull of Sartine - is in one of the few non-linear sections of the dungeon and (gasp!) behind a secret door. Admittedly, the DC 25 Perception check is terribly easy for most groups - they should pick it up passively by now if anyone's trained in it. It might be work making it a bit harder if you want them to work for it.
Roleplaying?
There's not much catered for in this section (save if you're actually paying attention to Moyshanna and giving her a personality). There are several monsters bright enough to interact with the PCs, but it'll generally be whilst they're attacking. Sigh.
The Efreeti could be fun to run as rather annoyed that it's been summoned to defend the tomb (by that dead woman?) away from its nice home in the City of Brass, but there really isn't much to work with.
Into the Shadowfell
The first encounter here is dreadfully important: the descriptive text mentions that the draconic wraiths are capturing "lights" (actually souls) and taking them to the fortress. Moyshanna will confirm that they're souls. This needs to be emphasized a lot because it's what the entire adventure turns on: someone in the fortress is stealing souls.
Assuming your PCs don't run away at this point because they're annoying people who don't want to play the adventure any more, you get the obligatory encounter before we move to the next dungeon. You were hoping for some wilderness action in the Shadowfell? So was I. Tough. More dungeon delving for us!
Magrathar's Teeth
This section covers the rooms and corridors within the wall that surrounds the fortress. You might ask "what happens if the PCs just fly over the wall and approach the fortress that way?" and it's a good question. Unfortunately, Bruce Cordell and Shawn Merwin were ready for you: you can't enter the fortress without possessing the four
soul rings that are found on the Big Bad's henchman's lieutenants within the walls.
Oh, and then you've got to find the Big Bad's henchman so you can reattune the rings. Alas, it's not by persuading him: you just need to kill him and take the Master Ring.
One of the interesting thing about the "Teeth" is that you're actually talking about miles and miles of corridors and rooms, but only a few are inhabited. (You can travel from one to another by following the tracks in the dust). When I get to this section, I'm going to probably throw in an escaped prisoner/shadar-kai or someone into an empty section just to give them someone friendly (if suspicious) to talk to.
There are four bosses to deal with here, so just a few notes on them:
Porapherah the Nightwalker and Xenro the Dracolich
One of the glories of the adventure, Xenro doesn't want to be a guardian, he wants to be free. So, he's quite happy to talk to the PCs, assuming someone speaks Draconic. There's a skill challenge here to deal with the parley, but I'm quite likely to roleplay it out instead. Assuming that happens, they can actually learn about the rings they need.
Porapherah, Xenro's boss, doesn't want this to happen and is astonishingly dull. He just attacks.
Vorst the Ice Archon
Another tremendously dull villain. He wants to kill the PCs. At least he has prisoners they can talk to. And he flees once bloodied. Hooray! A smart villain!
Dedanum the Azer
Dedanum is yet again, dull. His realm of five encounters - which is probably too long - isn't that dull, however. It's under attack by the Far Realm. Oh, and you get to debate with sage ghosts. What this section really needs are more monsters that could be persuaded to (a) run away or (b) change sides. Too many are written as "will defend the room at any cost". Boring! Have fun with this section; I intend to.
Zry the Slaad
I love the Slaad, but this is a pretty dull section with a lot of combat and not much else. And then you get to fight the Big Henchman, who - at least - has a great opening speech where he mocks the PCs.
This entire section will take several sessions (perhaps one per small boss monster) to get through. Sigh. The combats are well-written, but there needs to be more items of interest to tantalize the PCs. You know: like evocative non-combat areas? Such as there were in the Tomb of Sartine?
If any part of the adventure needs cutting down, it's this bit. I'm not sure if I'll get around to it, but you might like to.
Entering Nightwyrm Fortress
Thankfully, we're only talking about five encounters here after the overlong Teeth section. They're not bad. Again, not much roleplaying - although Varun the Rakshasa makes up for a lot of that. (Oh, for some interesting neutrals!)
There's some important information to be learnt here (at last - hooray!) and the final combat might be fun... although Solo Lurker + 3 Skirmishers is likely to be an annoying combat. Take note that the Skirmisher Wraiths don't join in until Urishtar's has been bloodied (and then require a minor action from Urishtar to do so).
So that's my quick summary of the adventure. It's one of the weaker adventures (especially compared to P2), but it's not without merit. The basic concept is great: it just needs more roleplaying and exploration elements. Pity Wizards are so bad at those recently.
Cheers!