I'll try to group my likes and dislikes so it's easier to read or skim over:
New Classes
Likes:
1) Paragon seems like a swiss army knife, even moreso than the Ritualist. I can play healer, buffer, and damage dealer in one build, and I'm loving it! (still loving my Rit, too)
2) The Dervish is still going to be a sweet soloer, I believe. Their unique AoEs and decent attack skills make for a killer tank.
Dislikes:
1) I think the Dervish was hit a bit too hard by the Mysticism nerf. That's the only beef I have with them right now.
Heroes
Likes:
1) Absolutely the best thing that ever happened to PvE, IMO. The henchies were great, the Heroes are phenomenal.
2) Customization, FTW. Just being able to change their skillbar is fantastic. The fact that you can equip their weapons and runes, control their skillbars, set their aggresiveness, and setup waypoints is above and beyond!
3) They have personality and are a more integral part of the storyline unlike henchies. I like having to take certain Heroes on certain quests/missions because of the important part they play.
4) Being able to use your own customized stuff is a nice feature.
Dislikes:
1) Wish they were just a little smarter and not so gung-ho while in aggressive mode. Defensive mode tends to make them stand around and not attack a lot, while Passive mode can actually make them run away, but into another mob threatening the whole group's survival.
2) The flag waypoints need to control Allied NPC's as well. It seems in-place so you can do maneuvers such as pulling, but Allied NPC's will ruin that entirely just as the old henchies do.
3) Need to be able to set a "priority skill" that they will use over any other. i thought that the check-mark did exactly that until I realized that all it did was buffer that skill to be used next, no matter what. You should be able to let a Hero know that "Watch Yourself!" and skills like it are a priority and should be spammed as much as possible.
Quests
Likes:
1) Tons of quests! The more the merrier! As long as they're not required, it's fun to have options.
2) Quests that are only available when certain criteria is met. There's a small handful of these in the other two games, but it seems prominent in Nightfall, and I love it! It makes the game seem alive and dependant on what you do.
3) Quest rewards are creative and quite useful. The promotion points are ingenious, and it feels like I'm gaining status within the Sunspears for doing oddjobs for people. Glad to see the "Quartermaster" rewards are still there. I thought that was a great idea in Factions and I'm glad to see it carried over.
Dislikes:
1) I was a bit sad to see that there were no skills as rewards to any quests. Even in Factions you at least got a good chunk of skills in the beginning to try out. In NF, you can only get about 8-10 for each class.
2) Any quest where you need to get a certain item or items to drop to complete the quest, please make the drop rate a little better, even if it's only while the quest is active. I never did finish the chef quest for that very reason.
Audio/Visual
Likes:
1) The game is absolutely beautiful! Landscapes, monsters, architecture, effects (love the zone portals!), character armors, and items are leaps and bounds ahead of Prophecies and Factions. People in the art team are getting paid well, I hope!
2) Jeremy Soule, you've outdone yourself. The music sets the mood so well. If I wasn't so caught up in everything else, I'd swear I was watching a movie with the score done by John Williams.
3) The battle music is an awesome addition. I know people were suggesting it and I'm glad Anet listened and stuck it in there. Adds a new dimension to battle.
4) Animation - just want to say I think the Dervish attacking with the Scythe is one of the coolest things I've ever seen. The way they hang their head after a killing blow just oozes mega-Fonzies. The dance animations are all sweet, too. Yes, even the female Paragon, I love it!
5) Cutscenes, lip synching, and voice acting... superb! I know it's been said over and over, but I commend thee! These improvements are long-awaited and much appreciated!
Dislikes:
Just a few glitches in sound effects to mention here...
1) Sometimes there's no sound effects right at the start of battle, as if it's washed out, then I can start hearing it.
2) Also, I noticed that when raising minions, the character goes through the motion, filling the progress bar, then the minion is raised, but at the finishing of the spell, the character just abruptly stops and it plays the 'clicking' sound as if the spell was cancelled, but yet the minion was raised. Not sure if it does it for all corpse-exploiting spells, but it is kinda annoying cause I have to make sure the spell was completed.
3) One more thing, about the battle music, it does seem to start at odd times. It shouldn't start just because you activated "Blood of the Master" or "Orison of Healing" when there's no enemies in sight. It makes me kinda freak out thinking we're being ambushed or something came up out of hte ground and is attacking us.
Oh, I can't wait till release! This is a very solid game and I think the amount of whiners with this chapter will be a LOT less than Factions. Personally, I had a hard time trying to come up with any dislikes, and I look at them as more "things I don't absolutely love", rather than dislikes.