I GM'd this at high tier, and I really enjoyed it. Several thing that could be tightened.
1) Finding a way to explain the politics of Crystalcrag without the Council leader simply telling the PC's everything.
2) The fight at the alchemist shop was well designed and the mechanics with the burning building was fun, but Martial Flexibility is a (insert obscenity here) to figure out with 4 lvl 7 brawlers. Maybe have their feats already factored in when the combat starts?
3) The faction missions were really not laid out for the PC's, and I felt like this could cause a lot of frustration at the end of the scenario, especially for newer players.
Tygora and her minions was a really fun encounter, and I felt like it could be very challenging for high lvl PC's when run by a crafty GM.
Overall, a really solid scenario and one I'd like to play in the future.