Pros: Comfort, fit, durability
I bought this medium flex boot in 2009 as my first piece of equipment after returning to active skiing after ~12 year layoff. I got it from Bill at Green Mountain Orthotic Lab (Stratton) who did a fantastic job of sizing me and making me custom footbeds for a reasonable price (I highly recommend him).
The boots were great for the first 5 years of use, but eventually I advanced in my technique and the flex wasn't stiff enough as I was able to engage more actively in the front of the shin. At that point I started having troubles with movement of the foot and ended up moving to a stiffer boot.
Overall I was very happy with the performance of these boots, and they still appear to be in great shape. I am going to pass them on to one of my friend's son, who is going to grow into the within a season or so.
I am 5'7", 165 lbs, and wear a size 7 EEE. I bought a 24.5 size boot.