It's an exceptionally well-written module. This is what you run/play if you can't run/play one of the Opens; it's written in a very similar style, and is suitably epic in nature (which is rarer for tier 3 modules).
Coming in at 100+ pages, there's a significant amount of prep work needed, especially in keeping track of things that have ramifications later on, and getting your head around some of the "if they do then, then this happens...", but this is the price of saving all of Faerun. Very engaging storyline with good formatting and grammar-checking. Even a few jokes that made me laugh out loud when prepping (e.g. oh how much of a difference a nanogram of weight makes).
The NPCs have been written with a solid basis yet adequate scope for the DM to be creative with them and play up certain quirks to make it engaging for both the DM and players.
There's a decent amount of roleplaying and problem-solving involved (it's not simply a combat-only module); by tier 3 characters often have many unique ways of solving situations without combat, which should be rewarded, but just as DM you'll need to keep an eye on time with some of these.
One of the downsides might be the rewards; I appreciate the author was probably bound by AL guidelines in how much they could offer, but for 8 hours of effort, some players might feel some additional rewards could have been warranted. Even cool trinkets, consumables or functional story rewards.
I'd like to see a tier 4 module eventually written to unfold other aspects to this story.
[5 of 5 Stars!]