From what I have read, it's a pretty solid book. It has lots of things that I will certainly pluck from.

The one change from earlier versions, is the the Baaz's on death effect. Instead of trapping the weapon, it now has a weak AOE petrification gas. It is a very minor nitpick, but the EVIL dm in me would prefer locking up a martial's weapon for a minute instead of having them do a bunch of easy saving throws that will only do something if they are entirely unlucky.

Also some of the Fizban side bars are a bit to stomach groaners, but some did get a chuckle from me, especially is side bar about the aspect of bahamut.