The metro in Delhi is pretty much brand new in prep for the commonwealth games but can be very crowded!
Delhi-very busy place, lots of people everywhere. be careful crossing streets and mind where you are placing you feet!
lots of friendly folk there but lots who are too friendly by UK standards-you may get stared at if you have pale skin/blonde hair etc. people may try to take pictures of you as you sleep on overnight trains!
A real culture shock so be prepared.
Bring immodium and some sort of fluid replacement powders etc as these are a help if you do get ill.