I enjoy playing and running PFS adventures. However, I'd like to recommend a couple of improvements to the scenarios.
1. Take stat blocks out of the text and include them as appendices by sub-tier, with no stat block spilling to another page. I find having the stat blocks for multiple sub-tiers right in the text, breaking across pages, to be difficult to use. I would much rather have an appendix for each sub-tier. Since we DMs print out the modules, I don't expect that page length is a concern to Paizo. I don't want the scenarios to have many extra pages, but the trade-off is that I wouldn't have to print stat blocks for other sub-tiers. I'd probably print less this way, in fact.
2. Provide a simple way to make each encounter a little more challenging. For example, I've run scenarios for 4 PCs at level 4 in sub-tier 3-4. Every time, they walk through the combats. This phenomenon is even more pronounced in sub-tier 1-2 with a group of 2nd level PCs. Perhaps provide one or two other creatures to the encounter, or a terrain obstacle or a buff (potion or scroll) for the enemies to use.
3. Eliminate sub-tier 1-2 and have a simple sub-tier 1. Then 2-3, 4-5, etc. There's just no comparison between 1st and 2nd level characters. Four 2nd level PCs have blasted through every sub-tier 1-2 scenario I've played or run. They're exponentially more powerful than 1st level, what with many more HP and the gear.
4. Provide read-aloud text that includes the creature(s) in the room. So many times, the read-aloud text describes the room, but leaves out the creatures/villains in the room. I recommend including that information with the excellent descriptive text. If, for some reason, the creature isn't there, it's easier for me to skip the text than to ad-lib it. And, the majority of the time, the creature will be there.
These are humble suggestions and I recognize there may be reasons they aren't feasible--reasons I haven't thought of. What do you all think?