Dear candidate,    

Iiit kalyani is not exactly best , but it is good for cse.

Iiits were solely created for cse and you will have ample of research opportunities , the curriculum also is brilliant.

Hope I answer your question and it's helpful.

Good luck

its clearly not a waste ! it is getting mentored by IIT kharagpur,which cleary gives a better hopes for the future there . 

since you are looking for CSE which is the best branch in almost every college across the  country. feel free to go there if u dont have any better options left . no institute is best or waste for any branch its just you who differ in between . if you are willing to work hard then no matter in which college you are  you can have edge over anyone.

since it comes under the IIIT tag and is a Govt. affliated insititute there should not be any problems going there provided there is no better option left.

good luck! see u in the field soon.