I haven't found a definitive answer about this subject in the help section so I'm asking here :
Can we ask a question that asks for reviewing a graphic design whether it is good or not ?
From your description here, it sounds like you have in mind what we call a critique question. They're on-topic, but with some criteria. Check out this meta question for more information: What are the guidelines for asking for a critique of my work?.
However, the question you've posted isn't really what I consider a critique question. You're asking about a specific graphic that you're working with, yet Ryan's answer is broad enough that it can be re-applied to different scenarios. Either way, I think the question is right at home here.