An excellent dungeon adventure module wiith charming NPCs and setup. The factions seem to make sense and have useful interactions that can be exploted by the party. Encounters and riddles are also creative and in my opinion not too unfair.
It has a very detailed description of the floating part, I just wished that the on the ground bit would be a bit more fleshed out. Whlie it has interesting locations and proposed strategies to make it up to Highfell, most of these details (and the hex map) are up to the DM to fill out.
Another small thing is the organisation where above and below ground dungeons are split into separate chapters, even if they are connected and logically the party would go directly from one to another (I haven't checked the PDF, some smart hyperlinking would solve that probably too).
Small bit of complaint is also the number of "empty room" in some of the maps, which on one hand can be filled in on the fly with "kitchen","store room", etc. but it would have been nice to have a word or two describing them.
And last but not least a quite a few shoutouts to other products of the author and cross referencing tables in them. Most DMs probably just ignore the results and reroll, but it does take extra space with not much benefit.