It takes awhile.
For one thing, the cards grow enormously upon import--one "card" in StoryNexus becomes at least two in Twine (which makes sense--cause, then effect!) but most of them become three or four (and in one epic case, twelve!)
The current arrangement is that when you're in Moon-Stuffing Camp, you'll get access to whatever quest lines are currently "live"--the Frog questline, for example, or talking to the Sorrowful Oryx or whatnot--and then you'll also have a random grind quest available. There's ten possibilities, one of which could come up at any given time. If you want to grind, you can, but you can also just ignore it in favor of something else, which will mean (hopefully!) less tedium than the StoryNexus version--you don't have to keep playing the same cards just to get them out of your hand and hope something more fun will come up.
There will also be a randomized merchant who will appear regularly but not every single time you visit. (Presumably Wool-tribe will be very similar, although I haven't started that section yet--working on Moon-Stuffing and Streamside at the moment.)
Kevin has very kindly built me a skill check function, which is awesome and saves on typing. Skills are probably going to build more slowly in this version (which is good, because they built comparatively fast in SN--a couple turns in Withyjack and you could max out Keen, for example) but since you will probably have unlimited turns, it should all work out. (There will be a lot of re-balancing in playtesting, I expect...)
Despite the fact that it's slow-going--on a good day, I can port maybe five or six cards, which, given there's 450+ in StoryNexus, means it'll be awhile!--there's a lot of cool stuff I'm able to do now. If I want someone's dialog to change based on your species, I can just DO it, not have to tediously set up six different nearly identical click-throughs. And with stuff like Frogquest, when you wander through camp, you actually get the Frog watching you and lurking and you see little wet footprints outside your yurt and things, even if you can't do anything about it until a little later. (Which I think is awesome, although the players may just go mad.)
I'm looking forward to actually getting to the storyline quests, rather than the grind stuff, although it's important to get those worked out, because that's where a lot of the important mechanics are, and if I break one of those, it's not nearly so crucial as if I break a major storyline.
(I am NOT looking forward to porting the Steppes section, although I've got some idea on how to do it--that's gonna require some revamping, and I expect it will take weeks to recreate properly. Oh well...)
*Used in the sense that you can do them repeatedly to build skills/make money, and they don't change significantly or advance the storyline.