Dhanbad is not a pretty city in the easy sense. It is loud, smoky, commercial, and tied more closely to coal than almost anywhere else in India. That is also why it is interesting: the city sits beside the Jharia coalfield, a landscape of mines, rail sidings, technical institutes, and working settlements that has powered much of eastern India's heavy industry.
The best reason to stop here is to see that industrial geography rather than to look for polished monuments. IIT (ISM) Dhanbad gives the city a handsome academic core, while Sudamdih Colliery points to the harder underground story. Around the edges are real escapes: Bhatinda Falls, Maithon Dam, and Topchanchi Lake.
Dhanbad is a better stop for curious travellers than for casual sightseeing. Come if you are already crossing Jharkhand or Bengal by rail and want a day that explains coal, water, and industry in this part of India.