What to expect from 18-55 ?

I just bought the Nex 5 twin kit lens 3 days ago.

I have been very happy with the cam in terms of size and handling.

My last cam is the Nikon D70 (with its kit len 18-70). The Nex 5 does do low light and noise much much better. But when I start to shoot RAW on Nex 5 with its kit lense (say at ISO200), it is not sharp at all even compare to the D70 with its 18-70.

Am I expecting too much from the nex 5 with kit len or I got a bad copy.

Alan