The question of whether he is a good “villain” doesn’t interest me as much as whether a good antogonist, which I’d say he is absolutely. His weak villainy or potential entire lack thereof is exactly what makes him interesting as a character. He’s just as unsure about his place in the universe as Rey, which makes him a good foil for her when he makes the wrong choices.

Besides that, whether “weak” or not he’s obviously very dangerous, and unpredictably so. His emotions allow him to make mistakes sure, some of which benefit the heroes, but many of which don’t. In some ways a Vader or a Maul is quite a bit less scary, because you know exactly what they want.