This isn't my first incest manga, nor will it probably be my last. Incest isn't something I go out of my way to read, but I don't mind it, especially when it's done well. Here, it was only so-so for me.
The development of the relationship has some good points and some bad. I think the mangaka needed to show the thoughts and psychological states of the characters a little bit more while they were developing the relationship in order for the romantic feelings to really be felt by the audience. Instead, if comes across a little bit like they got together just because they were only around each other at the time, which doesn't happen without actual attraction between two people. The attraction was missing for me.
On top of that, the supernatural element (the time travel), while I appreciate it as an inventive way for the two to meet and fall in love, wasn't really explained well. It kind of just happened... no real explanation why it would happen at those times, what caused it, or anything else. Of course, it's a supernatural element so things like that don't need to be explained, right? Sure, if you want to go with contrived plots. When the time travel is the only thing that makes your story happen, the only supernatural element in your story and it only happens at points it needs to for story telling, then it's way too contrived for my appreciation.
Also, the ending felt a little rushed and unresolved. Basically, the whole plot could've worked better toward a clear end that felt satisfying, and while it made a valiant effort to do so, it fell short.
So why did I rate it so high? Well, it's cute enough as a story. The art is decent. There is some proper character development (though I'm kind of strict on character development in a story and it wasn't satisfactory for me). And overall you can do worse if you're looking for an incest story (much worse -_-;; ). My overall thoughts are you can read this one if bored or if you're looking for something with these kind of elements in it (father/son relationship with time travel), but don't expect a masterpiece.