Hi, Hope You are doing great!

Taking Btech+Mtech dual course is always a good idea lets see some positive and negative points:

Positive Point
1. You get both the degrees and you save a year.

2. You will specialize in a particular field of your engineering or science stream.

3. You have a higher number of firms who come to recruit you and also offers a higher salary for dual degree students

Negative Point
1. There are not many negative point but Sometimes students don't want to do PG in engineering rather they go for MBA or UPSC or pick up a job or pursue any thing apart from these options.
2. Students who does not get IIT for Btech have desire to do M.Tech from IIT and prepare for GATE exam.