What more can I add. It's long, the art is like in oldschool shounen manga, but the manga itself is more like smut than shounen (the jerk of a male lead is like straight out of oldschool shounen though). There is probably more plot going on in this series than in an actual smut manga though.

This manga isn't exactly consistent when it comes to smut, some volumes have a lot of it while some have very little. Regardless of that, sex is present (at first mostly offscreen) from the early chapters. The main due become a couple early on, but through the course of the story many love rivals appear for both of them. While it doesn't become the main theme of the series, there is some infidelity in it too. Something like this happens at least once for both characters, but they also did date other people (with lesser consequence) to keep their forbidden student x teacher relationship a secret.

IMHO, this manga isn't extremely good. At first it was interesting to see how the author managed to make it mature without turning the series H (which is how manga seems to work nowadays) and I guess there was fair amount of romance. Later on, it becomes too smut-like and the male lead starts to get on your nerves. He is a jerk, he is just a teen, but he smokes a lot, drinks a lot and bangs his teacher. The female lead can get annoying too. She has moments where she becomes completely defenseless against men hitting on her, just like a heroine of a cheesy smut manga.