The green scar was the first adventure I ever made it all the way through as a GM, in any system. I had a little trouble running it during the first act of the adventure, but that may be due to the fact that I'm but a young'un with regards to running an rpg. The next two acts were very enjoyable and provided a lot of interesting stuff to work with, culminating in a final battle that was really a blast and left me and my players excited for more.
The first act was what I had issue with the most, mainly due to it's messing around with time travel and what I found to be a very weak plot hook. It took by far the most sessions and the players felt no motivation to move forward, and even with me explicitly stating the goals of the party, they had trouble trying to figure out HOW to even accomplish their goal. There are areas within the starting temple that transport you to different places in time, and some of the suggested hard moves actually encourage you to pop one of the players into a differnt time zone for no real reason. It was confusing and had no bearing on the rest of the adventure. I'd suggest omitting the time travel alltogether, unless you make the whole party travel together no matter what the circumstance.
It's detailed, but the layout could definitely have used some work, in my opinion. The biggest issue for me was the maps, which were simply poorly constructed within the main pdf. Instead of labels, they simply had circled drawn around areas of interest, and the names of those areas were listed underneath the map from left to right. So, the farthest left circle would correspond with the top of the list, and the farthest right circle would correspond with the bottom. This led to a lot of wasted time trying to figure out what was where during the first act, and I eventually just wrote the locations in on my printed copy of the pdf.
Also, finding the stats for enemies was tough, but I realized just before writing this review that there's a bestiary pdf included which has the stats and motivations of the enemies, so I'd recommend having that handy while you run the adventure.