Now... I've already commented on this VN elsewhere, at least to a point. So, I'll just do a quick recap of my initial feelings on this VN. I'll go ahead and get the negative out of the way first.
First, the common, Sara, and Karen routes... as I've said elsewhere, these routes exist solely to give you certain information that adds depth to the story of Rinne and Setsuna. So, lolicons and fans of heroines like Karen, you are wasting your time if you go into this VN if you are expecting something truly great out of those two. Sadly, those routes are about as weak as some of the worst charage routes I've played.
Things change dramatically during the Rinne, Winter, and Summer routes (they extend from one another). The degree of character development quality, story-writing, and narrative is incomparably better than that of the common and sub-heroine routes. This is perhaps inevitable, as this VN is basically a kinetic novel using chameleon-like techniques to make itself look like a normal multi-path VN. Do you think I'm joking? I'm not, seriously.
I'm going to be blunt... I wasn't moved emotionally at all until the Rinne route. I can honestly say that if you are looking for emotional stimulation, the Rinne>Winter>Summer progression is ideal. There is a lot of mindfucking involved (those who compared this to other VNs with similar themes are more or less correct). The biggest complaint I might decide to bring up would be a very simple one... in the VN's 'true' ending (there is a 'good' and a 'true' one, whose actual names I won't reveal, since they are spoilers) the story as a whole isn't actually brought to a resolution. Of course, there is a definite sense of hope that comes out of it, but the writer chose to leave the story unresolved, probably for similar reasons to the people who did so with other VNs of the type.
Intellectually, this VN isn't nearly as stimulating as you might think. For one thing, the protagonist is too much of an idiot to grasp most of what is going on. For another, there isn't much food for thought that hasn't already been covered if you've taken an advanced physics course or two (at least conceptually). The humor in this VN tends toward shimoneta (sexual humor), which is kind of ironic, considering it is an all-ages VN. I honestly enjoyed the humorous character interplay in the various paths, and they did a really good job in the latter half of the game of bringing the various characters and the settings to life. Edit: One thought that occurs to me is that this might be intellectually stimulating if you aren't accustomed to juggling sci-fi and science fiction weirdness, such as the stuff from the Hyperion book series. The protagonist's perspective in this VN isn't so much ignorant as limited by his own psychological immaturity (like a five year old in an adult's body, his immaturity enforced and reinforced by his amnesiac state).
Is this a kamige? No. Three elements make this an impossibility... the common, Karen, and Sara routes, the inconclusive final ending, and the somewhat stale attempt (in my eyes, at least) at intellectual stimulation. However, this is definitely one of those VNs I'll name as 'one to remember from 2016'. It won't make it onto my personal favorites list, because I intensely dislike inconclusive endings, but it is still worth mentioning, just as many flawed VNs I've played have been.
Overall... this VN will probably appeal to the sci-fi mystery crowd and inveterate romantics (love across time, lol) the most. This isn't a moe-type story, despite the art style, but it does take a page from the playbook at times. This is also a relatively short VN, considering how much content they tried to force into it... think about seventeen hours of playtime, total (that is what my clock is saying, anyway). It is about the same length as an medium-length charage, so that isn't necessarily short... but for a story-focused VN that is pretty short. If you were to ask me straight out whether I liked it as a whole, I'd say yes, but if you ask me if I'll replay it, I'll say 'only if they remake the ending'.