i have also read the reviews on http://www.notebookcheck.net
and found some cons in samsung np550p5c like display quality is not so good though it has anti reflective screen, aslo it has some heating problem and u can also check the default clock speeds of nvidia gt 650m in both the laptops..
samsung-2gb ddr3-deafault core clock 410 MHz,memory=900 MHz,turbo core clock upto 950 MHz
dell-2gb ddr5-deafault core clock 745 MHz,memory=1000 MHZ,turbo core clock=835 MHz
Again on heavy loading both the laptops drops to their original core clock speeds..If that happens then the performance of samsung will drop to a very low level(410MHz) which is not in the case of dell(745 MHz)..