I haven't installed and tried these out yet, just read the release notes. Both Illustrator and Photoshop support OT variable fonts now (October 2017 release). I also noted that Illustrator (at last!) supports stylistic sets.
Illustrator CC release notesPhotoshop CC release notes
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And as a side note, the Fall Creator's Update (Windows) also ships with a variable font. It's a DIN-alike font.
Acumin was already a favorite classic grotesque for me, so this will be nice to have. And of course getting axis-based Myriad and Minion back after 15 years away will be lovely.
In Photoshop it is much better as shows the (named) siders directly in the character panel.
Illustrator: the axis controls disappear whenever you aren't actually adjusting them, with no display of values anywhere, not even in the style field. So normally you can't even see the axis values of currently selected text!
Photoshop: the axes are in a "Properties" panel separated from the "Character" panel. Clicking on the "advanced" button in the Properties panel brings up the Character panel and makes the axes go away.
Photoshop at least displays current instance info in the Style field, which is very nice.
Additionally, in Illustrator (at least) there are some serious bugs in the handling, and text frequently goes completely haywire when switching fonts and adjusting axes.