I hear you on the Imu being a bit boring bit tbh, but I think the reason why he feels a bit boring is coz Oda's restraining his bag either for the climax or for the final war & also making him passive to stall for time. We've seen what Imu can do when he's a bit more proactive. He dispatched Loki quicktime and negged Luffy in 1~2 chapters.
Reckon we will see peak Imu once the wings fights progress a bit more. Fact that we are still yet to see hybrid Loki I think is evidence that there is till more to come yet in this fight.
It's not about his techniques he did well beter than kaidou in my opinion.
But as characters I dont enjoy him at all
Other than talking in 3rd person like someone above everyone, he only has angry reactions or coughing blood
He is empty as chapter.
Usually villains are either laughing and mucking mc or being badass in some situations
But imu is just like a doll
...
The only thing that may change later is his last fight if it was 1 vs 1 with goofy .