The train from North East to Delhi is the worst, man. It always comes mad late at night. It's hella crowded with people without reservations and those on the waiting list because of too many stops. If you gotta travel in SL class, take the Poorvattar Sampark Kranti instead. It's also never on time, but at least you'll get to Delhi by 6-7 pm, which is way better than the Northeast Express that reaches around 10.30-11 pm or even 1-2 am sometimes. If you can afford it, always go for the Rajdhani in AC class. It's on time, saves time and totally worth the extra cash.