The Garden State Parkway has two different personalities. South of the Raritan River, the parkway reflects the design principles of the Robert Moses-Gilmore Clarke school that brought us the great parkways of 20th century New York. North of the Raritan River, the parkway is strictly functional as a suburban commuter road, and performs rather well in this capacity.
Two major drawbacks of the parkway are as follows:
The speed and lane changes at the 11 barrier toll plazas are a traffic hazard, and the frequency of the plazas (every 15 to 20 miles or so) only exacerbates the congestion. One solution to this problem would be to construct highway-speed EZ-Pass lanes.
There is no consistent signing standard for the destination ("big-green") signs along the parkway. One could hope that the consolidation of the New Jersey Highway Authority (which ran the parkway until July 2003) and the New Jersey Turnpike Authority would bring about consistent signing, but this would be a tall order.
Congestion is a problem during rush hour (in the north) and summer weekends (in the south), but this is to be expected. Nevertheless, the southerly 125 miles stretches of the parkway are a pleasure to drive.