Quality of headsets

Recently, my friend bought a smartphone, Sony Xperia L.

There are various things provided by Sony e.g. Walkman, CyberShot, etc. which are embedded in this phone.
When I listened to the music, I came to know that the headset provided is one with 3.5 jack.
I had Sony Walkman back in the days, with those heavy headsets, which gave a fantastic quality sound.

I think, the hardware has caused the sound quality to hamper, what is your opinion?