You also can't point/shoot/eject/watch-it-develop like you could the original Polaroid. The Impossible film remains sensitive to light for at least 10-15 seconds if not longer, requiring hacks and tricks to eject it into either a box or under shade to make it develop properly at all.
Those issues have actually--finally--been resolved in the latest generations of Impossible's film; it only started shipping a few months ago.
I haven't tried the new color film, but I have used the "Generation 2.0" B&W film--which does appear to be as much of an improvement as they say.
all for vintage pictures that look like they're 40 years old the minute they fully develop.
I guess it's highly subjective, but that seems to be part of the appeal of Impossible's stuff. When I first saw the way my pictures on the colour film ended up, what really struck me was that it "didn't look real, it looked like a memory". And the experience of "watching a memory develop" was kind of profound.
I wondered whether the uncannily-matched fuzzy hypercolor in the way I experience memories and dreams was perhaps due to my having grown up with polaroids and basically been calibrated to that "being what memories look like". But then I actually found some old Polaroid pictures, and you're right: they weren't like that. So, I don't know where it comes from. But I like it.