If a thing can be made by both NX Shape Realize and part modeling
then what considerations should be taken in mind to select the best method.
If you're not resricted about dimensions, you may use realize shape. It's much easier and enjoyable.
As Mustafa said, if you're not working to styling requirements of .xx tolerance then it's a great tool. For totally free-form efforts, conceptual design, etc., it's the fastest tool for the job.