Well, a very enjoyable film indeed in both style and execution, which works well as a romantic story even beyond the core issue it wants to deal with. The reason for it is probably that at the end of the day it is not really a core issue but just a plot element, and it's handled very subtly. What this film has going for it after all is its lovely romance and how beautifully it celebrates the Indian culture. Just to think that a decade before big banners were so pathetically obsessed with making films about Indians living abroad when there's so much to explore in India itself, which happens to be one of the most culturally rich places in the world. The film, through its nice story both embraces tradition in many ways but at the same time defies it more than once, making it an interesting study of the new life of Indian middle-class youth. They respect elders, they accept traditional customs of arranged marriages and everything that comes with it, but they have no qualms about premarital sex.
The film is technically impressive, it's natural and authentic, and above all it's humorous and wonderfully charming in its simplicity and comic tone. The dialogue is most casual and realistic, the story develops really well, and it manages to turn its core issue (the guy has what they call erectile dysfunction, a formal name for his actual struggle to engage spontaneously in sexual activity, probably due to being too nervous), as mentioned above, not all that central. It is the larger message of the story that provides a meaningful commentary on gender stereotypes of masculinity, on the pressure that new-age relationships place on today's often unassuming youth, and basically on the loss of innocence which manifests in over-exposure to the big world (and the west, in particular), and, in turn, demands everyone to meet some pretty high social expectations. It is this message of the film which thinking youngsters might like and relate to, and even the less thinking ones might become less judgemental.
All of what the film addresses is brilliantly encapsulated in Ayushmann Khuranna's compassionate performance. He manages to make his character an unlikely hero because he is as funny in his problem in the context of the story as he is touching in his obvious insecurity, always drawing the viewers' sympathy and affection. You really feel for him through his struggle and want him to get over it. What makes the story all the more so substantial in this regard is that he actually speaks about it (or hints at it), something few would probably do. His leading lady is the immensely pretty and likable Bhumi Pednekar, who is the right mix of sweet innocence and smart sophistication. Her gradual change throughout the story is very well done, and she shows great understanding and sensitivity. She really gives the vibes of a simple small-town girl. Shubh Mangal Saavdhan is a nice little film, a charming romantic comedy which is entertaining but also very educative and meaningful.