I have always liked 1-2-3 quite a bit - perhaps I'm biased because I grew up a stone's throw from the Zinsser facilities in Somerset, NJ.
But frankly, this new batch is heads-and-shoulders above any previous version I've ever used, as far as the brushability. Honestly, it felt just like I was brushing out Aura or a high-end D-E paint. And when it dried, I swear I can't pick out a single brush mark or any roller stipple at all. The 7 interior doors I painted today are some of the best-looking finishes I've ever produced - and the doors are almost 100 years old, and spent the last 20-some years as a rental. I credit these results to the 1-2-3 that was used.
Oh, and normally I also use Extender and/or thin my 1-2-3 - but this time I only added tint, no thinning or conditioning whatsoever. I did check the label on the new 5, no obvious changes from the older one - same VOC, same solids content, etc.