Not worth paying premium price for any current gen game at the moment IMO... except for GTA V
Even if you're not getting a new console on launch I expect current gen game prices to take even a small hit by Christmas.
And yeah, V does look a heap better. Looks like what IV should have been. After San Andreas I don't know why they suddenly left out all the stuff like car modding and general debauchery. I still enjoyed IV for the story (Rockstar can write a good narrative) but it just didn't have the feeling.