Judging it from the standard of smutty BL, this is really good. The art is nice, the smut lewd and filthy. Even the bits of interaction are sweet. But the unfortunate thing is that it is SAMEY. There are two couples here, a pair of teachers and a pair of students. But SOMEHOW the story writes the exact same personality and uses the exact same dynamics for these two pairs. Other than a scant few of superficial details, it feels like reading a story about one couple rather than two. Again, that is hella unfortunate. Because a more varied dynamics and characters will not only create a more interestingstory, but it will also provide a wider variety of smut and fluff.

It's still a very good smut, but...yeah. Missed opportunity.