Different strokes for different folks. I think the art style is fine. Not every comic needs to have a complex style. I do see the hint of shipping them, but I really doubt it will go down that path... unless it turns out the girl he made the promise to is dead....
Edit; Okay, I hadn't read all the chapters when I made that comment. She's alive, so yeah there is something between them but I still think she's the one he'll end up with not the MC.