Edit (11/17/19): I'm knocking the rating down from 2 lippies to 1 because, over a year later, I'm still searching for a foundation that can compare to the old formulation of this one. Everything I've tried since then breaks me out or separates and slides off my face in no time. I truly consider the seemingly unnecessary reformulation of this foundation to mark the steady decline in the quality of my skin. They took something I loved and relied on for over a decade and just absolutely destroyed it, and I'm obviously still very salty about it.
This has been my go-to foundation since high school (in my early 30s now). It didn't break me out; provided good, buildable coverage; a great color match; a matte finish that helped control oil; and lasted most of the day on my oily skin. It practically checked all my boxes.
However, I picked up a new bottle 1-2 months ago and almost immediately noticed some differences in the formula and overall appearance---at least a shade darker than the ivory 100 that I've used forever; oxidizes upon drydown; sheerer coverage that doesn't layer as well; separates and becomes blotchy on my face after ~4-5 hours of wear, regardless of setting powder used. The main (major) disappointment for me, though, is that within 2-3 days of wearing it, I began to break out pretty badly, especially in places that rarely break out. I also noticed that after washing my makeup off at night, my skin just started looking... bad. Clogged pores, uneven tone, rough texture... my skin looked and felt like sandpaper.
This led me to inspect the labels on the old and new bottles of the foundation, and, lo and behold, they have upped the salicylic acid content from 0.5% to 2.0%! This increase may not seem like much, but for people who regularly use skincare products containing acids/chemicals (like myself), this foundation could possibly interfere with those products and cause reactions/irritation/breakouts. From what I could tell, there was no label on the bottle indicating a new/improved formula, so I wanted to point this out in case it could help those using acids or those with sensitive skin.