One thing to watch out for with a game this old, is grizzled old opinions. So opinions about solo play, the AI, the manual, vanilla (unmodded) Dom3 is abit colored by this point by the passage of time. People say disparaging things forgetting how many months they totally enjoyed it when they first got it.
As far as the manual, there is an errata page on the player-edited wiki.
http://dom3.servegame.com/wiki/Manual_errata
Out of 300 pages of the manual there are only about a dozen true errata listed. Im also quite happy that Shrapnel realized to ring-bind a manual that large so that it lays comfortable open while its in use.
Another necessary addition to the Manual is the log of changes from the many free updates and upgrades we have received. Here is the link to the page to get the patch (you only need the latest one) and below that in the same section is a link to View Patch History which is the only complete list I know of for all of the changes.
http://www.shrapnelgames.com/Illwint...DOM3_page.html