This Kelana Jaya extension line opened about a month already. From Putra Heights to KL is now a breeze... but ticket fee is not cheap. One way fee is around Rm5, but it is slightly cheaper if u use prepaid card like Touch&Go card. Senior citizens and students can apply for concession cards and fees are 50% cheaper.
I tried it out last week... to my surprise the 4-coach train is all jam-pack when i reached Kelana Jaya station ( i started at Usj7 station)