Only the first pair was worth reading and I wanted to see a lot more from them, this style with changing MC's pisses me off. If I had known this in the beginning I wouldn't have started reading this in the first place.
@TetsuyaLP: There's nothing left to discuss with them, though. The students graduated and are engaged to their girflriends/former teachers. This manga is clearly not designed to focus on the "happily ever afters" after they get together; only the sexy mishaps as they get together.