CPU performance is the same and maybe in some benchmarks less performing as Intel Dude said.
I've seen similarity in many website but Intel Dude is right Haswell is focusing more on less power consumption more than pushing for performance but from another point of you games are more and more focusing on graphics processing more than putting the load on CPU coz generally speaking not all games will use all the cores you have, but i could be wrong here.
So the only difference is with the GPU if ur targeting the GTX770m and the GTX780m then yes u will find the upgrade worthwhile and with some OC u will get a fair amount of performance
I have the G75VW with GTX 670m and it serves me well until now i have it since septembre 2012 with some OC it gives me good performance for current gen games and maybe for games released in the future hoping that Nvidia keeps us happy with good drivers.
If your a guy who wants to crank everything to max , ultra all the time and you have the money than by all means go for it 770m and 780m are the way to go.
Let us know if you have further questions.
Thanks