Looks like it'd be ok. For benchmarks look at this site:
http://www.notebookcheck.net/NVIDIA-GeForce-GTX-965M.134120.0.html
(Games are near the bottom, the website is very slow.)
FYI,
"GTX 970M (1280 shader, 192-bit GDDR5) is a further 35 to 40 percent faster." Notebookcheck.net
flamefire999 is wrong... the amount of VRAM does not give you better frame rates unless you are running like 4K resolutions.
It's all about the chip not the amount of VRAM.
But... in most cases he is right about alienware being overpriced. I do however believe the one you are looking at is fairly priced.
But, ya the 860M gpu in the Y50 Lenovo laptops is NOT faster than the 965M according to laptopcheck it's about the same as a 870M.