As a former Civil student at IIEST, my answer especially concerns my branch.
Before pursuing an M.Tech, you must keep your aim straight. It should either be to work in a design company, or opt for a Phd. This is because B.Tech is a much better degree if your aim is to get placed with a good package.
The placements for B.Tech are much better than M.Tech, at IIEST Shibpur. Some M.Tech departments offer decent placements, while others aren’t even average in this respect. But the teaching is really good for all departments.
My answer isn’t very particular, but I tried to give you a general idea of the placement scenario for M.Tech at IIEST.