Iasthai is an excellent level and well worth your time. It is distinctive both for its grounded setting and its treatment of heavy thematic material—pain, loss, illness, recovery.
Something Iasthai has in spades is vibes. Careful attention was paid to the packaging (icon, info screen, fonts, cutscenes), setting the stage for a diverse and venerable library of tilesets, thoughtfully curated soundtrack, and interesting screen compositions. Notably, the interiors are consistently top shelf (Lucinda's inner Sims player is on display here).
The writing is another highlight. Iasthai somehow manages to flit seamlessly between comedic exchanges with quirky characters and solemn meditations on pain. The narrative is nonlinear, even labyrinthine, and this structure lends itself well to the subject at hand: healing is rarely a lucid or linear process. I'm reminded of John Green's musing in Turtles All the Way Down that "in some ways pain is the opposite of language." Iasthai's honest prose finds a chink in that barrier of incommunicability, admitting a brief glimpse into others' inner worlds.
If I had to find something to criticize, some outdoor areas don't live up to the standard of polish I came to expect from this level. The challenges didn't add much to the experience for me; I think I would have preferred it to be easier, resting on the strength of its writing and environments, or for challenges to be employed more judiciously to advance the story.
In my book, Iasthai is an instant classic that pushes the storytelling boundaries of the Knytt canon. I look forward to your future work.