There should be NJAC as even the judiciary needs to be transparent and accountable to someone. The doctrine of checks and balances should be applied to judiciary as well.
The judiciary can't expect the other organs of the government to be transparent and be itself opaque. For eg. the judiciary isn't completely compliant of the RTI act as well.
For the credibility of the judges to stay intact, it has to begin with a transparent selection of the judges for the highest positions.
There are concers of nepotism and corruption within judiciary and hence it is imperative to restore its reputation. Otherwise the cases determined by the highest curts would carry no cridibility among the people.
Justice should not be just served by has to be seen to be served.
Yes there are concerns of the executive controlling the judicial appointments and the courts are vary as it has experienced the period of EMERGENCY in India. Suitable mechanisms need to be figured out to quell the concers and a common ground needs to be agreed upon to put an end to the speculations about the apointment procedures.