You're correct; Imu's past still isn't revealed, his appearance is still a silhouette and Imu is in action just
now.
Meanwhile you have Kaido who already got his entire saga with his connections to several dangerous pirates, which includes the whole underground. He was the reason the smile factory was created and Kaido was ultimately defeated in an all out war between two emperors and the alliance between the supernovas. In all these chapters, we've seen dozens of contradictions when it comes to Kaido's character. He's being portrayed as a brute who pretends to be an honorable "I'm the strongest!" brawler, gets pissed when someone interrupts his battles but somehow ducks at the slightest chance for a re-match - see Lolden - or sneak attacks one of his closest friends, Big Mom.
He talks about pirates betraying each other as if he was the one who got betrayed in the past. Now it turns out, he was the one betraying Big Mom at the end when he was hitting her from behind. He wants to die... yet does nothing valuable about it. Kaido's character is based on pure "The stronger beast eats the weakling" but in important circumstances, he either won by underhanded methods or straight up used these. To make things worse, he just got a few panels in his own flashback which is a complete joke.
This flashback kinda redeemed his character a bit when Kaido was shown to be more cheerful but man, Oda still can't help to add loopholes into his character.
So again, until we see Imu's flashback, his actual goals why he is currently leading the world and WHO Imu even is - your "criticism" is just one thing: completely void of any rationality whilst pulling out some hypocritical nonsense... because you are wanking a character who is the definition of "generic evil man brute" and whose character arc is already over while you criticize the very same things to the potential final villain whom we don't even know how this person looks like.
What is there to criticize about when we do not even know much about this guy to begin with?
Your actual criticism:
"he's just a generic evil man child" cool, how can you tell? Did Oda tell you why Imu is acting like that?
"no personality at all" how can you even tell this when this guy is still in a silhouette? Did Kaido have a personality when he was looking like this?
Yeah, figures...
Now, we know Kaido's entire character and it's just all over the place.
Like I said, Oda still tries to make a mystery out of Imu because the One Piece world - or us readers - have yet to find out
what Imu truly is. Sure, we can speculate about him being the Earth God or the Demon King but that's the thing - nothing of that sort is confirmed. So again, I have no idea why this is supposed to be valid criticism but whatever, lol.
???
What is there to analyze about when we lack fundamental information to begin with? You cannot start analyzing his character when the author still tries to paint this character as a mystery whose entire identity is yet to be discovered. THAT just shows a lack of argument.
Furthermore, you didn't analyze a thing. That is the difference.
You stated how boring and generic Imu is as a villain and when someone told you "Buddy, you're literally wanking the embodiment of contradictory when it comes to character execution" and you went all defensive all of a sudden, lmao.
Cool, and I am willing to bring Kaido into it. I guess you gotta live with it lol.
Furthermore, I brought Kaido into it to compare two characters to each other - to have a clear reference when we can either say: "Look, Imu is boring and generic unlike Kaido who is the embodiment of strength and honor when he was facing 30 enemies all on his own without using underhanded methods to overpower each and everyone of them!" or "Imu is pretty boring and a generic villain just like Kaido who is the generic "I'm stronk!!!" brute who is suicidal on the one hand, honorable on the other hand and sneaky on both hands which shows his lack of stable character."
So again, if Kaido has no real flaws, you would have to issues to refute my arguments by simply bringing up arguments in favor of Kaido. See, GeneralP123 has done it quite well although I still disagree with his takes.
Wrong; there is some... defence for how empty Imu is...
For starters, this guy. Is. Still. In. His. Silhouette.
I guess that's a start?