Naushad belongs to the old school of Indian music directors, widely recognized as one of the greatest, composing scores to a number of major Bollywood classics such as 'Mother India' (1957) and 'Mughal-e-Azam' (1960). I'm not sure if 'Saathi' is considered a classic; the soundtrack is certainly one though. Not in the usual as-perceived-by-hip-western-listeners sense, all beats and funk and rock 'n' roll etc. - Naushad didn't incorporate non-Indian elements into his compositions that often - it's great because of its haunting beauty.
Listen to 'Mere Jeevan Saathi' (which in fact does have non-Indian elements) with its sublime intro and wonderful melody. Or the moody 'Bhool Ja' (the intro to that had me thinking 'Saathi' might be a horror movie; it's not), or the two great 'Mera Pyar Bhi Tu Hai's. And savour the exquisite orchestrations throughout.
A wonderful album, I love it!
1. Lata Mangeshkar: Mere Jeevan Saathi
2. Mukesh: Husn-E-Jaanaa
3. Mukesh & Suman Kalyanpur: Mera Pyar Bhi Tu Hai (Happy)
4. Mukesh: Aankhen Khulee Thhen
5. Lata Mangeshkar: Yeh Kaun Aaya
6. Mukesh: Bhool Ja
7. Lata Mangeshkar: Main To Pyar Se
8. Mukesh & Suman Kalyanpur: Mera Pyar Bhi Tu Hai (Sad)