Disclaimer: I haven't watched the show beyond a few episodes before. Also, I am not a KSG fan at all. At all. But I hope to be neutral in my judgement. Otherwise, there is no value to any judgement.
Now, regarding Bajaj, it's only his first episode but I liked this version of Bajaj. I can explain why. This character reminds me of Ekta's vintage heroes from her glory days such as Angad, Sujal, Robbie, Arjun etc who were always morally flawed, angsty and borderline problematic. She has mellowed her heroes down to a very black-white level complexity now and I personally am not a fan. I don't particularly enjoy ~bad boys onscreen but there should be some layers, some intriguing qualities to a hero-figure. Ekta's current Bajaj is an obvious throwback to her vintage heroes. But I feel her team is just not capable of exploring this sort of character anymore. Her current shows and (most) newer characters are essentially mono-dimensional and bland. All thanks to her boring KKB-formula. She simply doesn't have it in her to construct and deconstruct characters like these. Not anymore. So it's pointless to expect her to do justice to this Bajaj.
Regarding KSG himself, I have heard plenty of complaints online since the morning so I was naturally predisposed to dislike him. But I surprisingly found myself enjoying the abrasiveness and confidence he brings to this version. Ronit's Bajaj was in a very different show, KSG's Bajaj fits into the environment of this particular show. This is only an unsure observation but I also feel that his acting is better now. More subtle and cinematic. He had a terrible tendency of breaking into television histrionics before. He is more balanced now. But this poses a problem. I can already visualize his relatively understated style being extremely out of place in this show.
Additionally, I think he still channels Armaan whenever he has to play a bold and confident character. Hence, his dialogue delivery falls into a hyper, slack-jawed style. Less of Armaan's levity and more of Asad's gravitas please.