I've been using their face pen for about a year now and quite like it, the one I used for years (also from MAC) was discontinued but I don't miss it because this one is way better.. not matte but less shiny, more coverage, more hydrating, higher SPF I think and you can just use it as a concealer. I think it's one of their newer foundations but don't quote me on that!
It's funny to see this activity in this thread and I'll take it as a sign because I'm running low on that pen and know I have to get a new one today. One 'downside' of this product is that when you run out, it's OUT, there's nothing you can't extract from it, not with a toothpick, or with a finger, nothing (because you pump it), if you don't have a backup foundation, you're destined to face the world and make it to the store with an uneven face (which I'm happy to do after a workout but somehow it feels like the walk of shame if it's because I ran out of foundation 🥲).
Forgot to add and not important but useful: you can lock this pen from the end of the tube and it's amazing because it won't ever make a mess in your bag or during/after a flight. 🥳