Dunki has an absolutely novel concept and premise; however the movie goes downhill from hereon, the crispness and freshness unique to Raju Hirani's storytelling is sadly missing here.
The movie did not need Shahrukh Khan - a lesser actor with no inherent image, personality and Shahrukh Khan'ness' would have been ideal. The other actors are very clearly "in awe" of SRK, and it shows with their clearly fanboying expressions and reactions - Vicky Kaushal is the only exception, he holds his own very well. The ideal casting IMHO would have been VK for SRK's role and Hirani favourite Jimmy Shergill for VK's role.
Editing could have been tighter as well.