First off, this is a backpacker's hotel in Pahar Ganj, so I'm reviewing it from that perspective - you're not going to find 5 star hotels in this category. Clean, safe and a helpful staff is a good find in this area, compared to mildewed, filthy and untrustworthy.
Major's Den is a basic backpacker's hotel. The rooms are simple (bed, couch, shelves) and scruffy, but clean and comfortable. We had our own bathroom with ample piping hot water (a major bonus in January, and not common) and extra blankets were available. It's definitely a bring your own toilet paper/towel/soap type of place, though. Being off the main bazaar it was pretty quiet (by Pahar Ganj standards).
The staff was friendly and very helpful, which is the main reason we came back on our second pass through Delhi. You can check your bags, and they will help with trains and booking a taxi to the airport.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC