Since my cousin used to be a student of IIT Dhanbad, I might be able to give you some facts about the college which might give you a proper insight.

• IIT ISM was formerly known as ISM Dhanbad. It boasted of a rich legacy and an equally rich infrastructure which is not true for the newly established IITs.
• IIT ISM is technically a new IIT but practically it is not.
• Because of the IIT tag, IIT Bhubaneswar and a number of other IITs had a very low opening and closing ranks.
• IIT ISM initially had a high opening and closing rank. Many candidates did not want to join IIT ISM even after cracking JEE.
• Many major companies visited the campus of IIT ISM during placements.
• The salary package has been going up and the number of companies visiting the campus has also been increasing.
• Some of the big names are PSUs namely OIL, MECL, CIL, IOCL, BPCL, ONGC, etc.

You can get a good job if you go for IIT ISM, as good as a job you can get from its Bhubaneswar counterpart.