Before he started making Bacchan blockbusters, Manmohan Desai had a try with many other good actors as well, namely Shammi Kapoor ("Bluffmaster") and Rajesh Khanna with this movie ("Saccha Juttha") amongst others.
There is a nice plot here and you can feel the Manmohan Desai touch throughout. Rajesh Khanna plays in a dual role, as a simple-tom who comes from a village into Bombay to make it big but instead falls upon his conniving double. A lot of intrigue and also good acting from Rajesh Khanna (who won a Best Actor for this film) and Mumtaz.
But to me, the voice of Kishore really steals the whole show, namely in the song "Meri Pyaari Behena". Kishore really transcends himself here and the end product is nothing but pure magic. Maestros Kalyandji Anandji are also to be commended for the composition, but the sincerity that Kishore brings to the song is nothing short of breathtaking. Not that Rafi and Lata did not have good songs (the duet "Yuhi Tum Mujse Baat" is spellbinding), but you have to understand that, at that time in his career, Kishore had reached almost perfection in his voice.
"Saccha Juttha" is a must for movie lovers with a keen ear for melody. It belongs to a golden period that isn't going to come back soon, unfortunately...