The letter goes on to discuss a couple of features (that may or may not have once been considered a part of the Will of a Tyrant update) that have been scrapped altogether. The Item Ratings system was abandoned, at least partially due to feedback from the player base, and the Fighter revamp that was in the works has been considerably scaled back. Both of these negatives do have a silver lining though -- the developers are looking at alternative ways to enhance gear, and Fighters will still see some tweaks, albeit "small changes, rather than sweeping revamps". Crusaders will be among the first Fighter classes to be looked at -- see the full letter for some early details.
While the producer's letter makes Will of a Tyrant sound overwhelmingly lacklustre, keep in mind that it doesn't go into some previously announced events that should give players something new to do for at least a little while. Hopefully the decision to squash all those bugs pays off with a smooth launch for Sentinel's Fate in February.