Kanpur Central is less a tourist attraction than a piece of north Indian infrastructure at full volume. Trains pour through from Delhi, Lucknow, Prayagraj, Varanasi, Kolkata, and Mumbai, and the station concourse is a constant churn of porters, chai sellers, families, students, and business travellers.
If you like railway stations, it is worth arriving early and watching the operation for a while. The building itself is not the main point; the scale of movement is. Keep your luggage close and avoid lingering outside late at night.