I was honestly hoping for less from the dungeon journal feature. I expected it to be more of an RP style like from the perspective of a past adventurer who may have come into contact with the boss and narrowly escaped or possibly died. For example, in Grim Batol a former Wildhammer Dwarf tries to return to his lost city to salvage something and encounters Forgemaster Throngus. He would write a description of his events in a style that does not completely give away all of the fine details, but may possibly give you some general idea like;
“Patrolling the halls of our great forge is an etten called Throngus. He carries with his many weapons of great devastation yet also has an impenetrable defence at times. Beware of his mace for it has the power to destroy … and so on”
This basically tells you enough about the fight to know there are going to be some times where you must proceed with caution, but leaves out the things that are just completely obvious. Don’t stand in fire; don’t stand under falling rocks; if fire is blowing in your face you may want to move.
I also feel like it’s completely unfair for this information to be free for all to use at any time. In my opinion the pages of your dungeon journal should be acquired within the instance of on certain quest lines throughout the game. Some things just need to be learned through trial and error. I think it would be nice for your journal to tell you about SOME of the abilities (from pages you have gathered) and other abilities you can only have documented after defeating the boss. I think a section of ‘discovered’ notes and ‘documented’ notes would be a better idea.
I can see why this is appealing to some folks, especially casual raiders like myself because it gets to be a little annoying when you walk into Bastion of Twilight and wipe on Halfus a bunch of times because people have no idea what the drakes do, but ultimately I agree with Lore and the other pro raiders that you need some element of surprise or you take the sand out of sandbox style play and replace it with… well… bricks?