Generally I think the level of difficulty is fairly spot on, normal being generally easy throughout and elite being a big jump up.
However, there are a few quests that are clearly much more difficult than normal. Proof is in the poison comes to mind, and Enter the Kobold.
I do not so much mind that EtK is difficult, it's more that I mind that the entire quest is a walkover until you get to the boss fight. I think that this makes for bad feelings when you have been leld to expect something other than what the quest turns out to be.
In the case of PiitP I think the rewards for actually running it ought to be turned up some, so the effort put into completing it can pay off.
There are also a few quests that are not so much "hard", but more annoying. East Threnal quest 3, and in some ways West Threnal quest 2 as well. I haven't run Faithful Departed in ages, but that at least used to be annoying too.
I do not mind that these quests take some skill to run, but it's annoying when the NPCs can be more or less one-shotted by mobs. Every other quest in the level range can be fairly easily soloed, but these can be very hard even in groups.
I would like these quests to be revisited and made less tedious. Especially the 15 minutes of pure agony that is East 3. Cutting down on quest length, upping rewards a little, and making the NPCs you're protecting more hardy would all be nice.
As regards to raids, I think it is a little silly to keep changing year-old raids around. People were still running those you changed, so I'm not sure what the point was. If you'd changed something like Titan instead, I'd have understood.
Also edit: While I'm not an uber powergamer, I have played for a long time, and do have both decent gear and (somewhat) thought-out builds. So that's the perspective my thoughts are from.
More edit: Dungeon scaling seems over the top. It's generally better to solo than to pug, which I think is a bad thing. Dcaling should be a help, not an incentive to not group up.