Well, the premise was pretty hilarious, but personally what killed it for me was the Mamoru bashing. It was unnecessary, and frankly, predictable and dull. It added a layer of vicious that basically undermined the lighthearted shenanigans. There are angles that could have been a whole lot funnier.
Usagi: ...and that's why I'm going to marry Ranma instead.
Mamoru: You... you mean you're leaving me?
Usagi: Well... yes.
Mamoru: you mean... I'm free!?
I always felt like Mamoru, as the Reincarnation of Prince Endymion, was in love with Usagi, Reincarnation of Princess Serenity. At the same time, the sour, solitary Chiba Mamoru really hates putting up with Usako's immature bullshit.
So yeah. Mamoru pulling a total Karma Houdini and escaping his True Love Destiny to, I don't know, graduate from medical school as was
his childhood dream, that would be fucking hilarious, too.
Especially if he interns with Doctor Tofu.