"D-Day, taut, gripping and incredibly made... a strong emotional layer that gives it gravitas... performances are top notch," Johar posted on microblogging site Twitter.
"Well-done Madhu Bhojwani and Monisha (Advani) for your debut production and Nikhil Advani for all the work and passion you guys have put in," added the filmmaker who had produced Advani's directorial venture "Kal Ho Naa Ho".
Kapoor also posted on his Twitter page: "Saw 'D-Day' last night. It is one of the best thrillers ever. Nikhil Advani is in absolute control of this fabulous movie-going experience."
"Arjun Rampal, can't get over it brother. What a magnificent job you have done," added Kapoor.
The film also features Huma Qureshi, Irrfan and Rishi Kapoor in lead roles.