Delhi Metro Rail has set standards for upcoming transit systems in other metros in India. It gives a fresh experience of urban travel, which is quite unlike any other transit system. The efficacy is obvious in different aspects like the use of smart cards, information exchange, intersection of different lines and even making available, some forms of NMT as a last mile connectivity option.
The website is also well laid out, especially the interactive route map can be really helpful for new comers.
However, the most exciting part of the metro is the Airport Express. Though it's still under development, the idea of reaching the airport in 21 minutes from New Delhi railway station is absolutely fantastic. Apart from the check-in facility at stations, the integration of this system at the airport is seamless, with a number of connectivity options at the new terminal. The train itself is well designed, considering luggage space requirements, and keeping the passengers well informed with active info-graphics.
There are very few reliable options at the New Delhi railway station though and the Airport Express station is near, but difficult to access from the New Delhi railway station.