Welcome to foundations! FDN had a pretty wide set of interesting cards for this environment. I do have more product of FDN arriving soon (tm), so there may be another update with more FDN, as the outlook of the next year of mtg is bleak.

The dream of Knighted Myr was always very cool, especially as it provided an overlap between the artifact and +1/+1 counter strategies, but it never worked how I had hoped.
The other changes continue to give more support to the artifact and counters themes, as the previous update gave some powerful additions to white sacrifice.

The madness cards were an interesting addition, but ultimately too narrow, so the addition of more flashback cards should serve a similar purpose to madness, but with more flexibility in decks that can use it.

In contrast to a previous change that looked to reduce the power of the reanimator strategies, this update gives some of the power back to the reanimation decks, by adding a better landcycler, several new reanimation spells, and a new target in the form of Archfiend's Vessel.

Unlike White, Red sees additional support to their sacrifice strategy, as previously Red was the weakest color of the intended main sacrifice colors, so this should make the Red Black and Red White sacrifice decks stronger.

Green sees the smallest set of changes, but is more focused on providing some minor tweaks to the +1/+1 counters cards to provide more overlaps in strategies.