Thats a moot point (jailbreak), quad core and retina display (potential 8 meg camera) are all worth while upgrades. Faster loading times for apps, awesome screen for videos and multitasking within web browsers made very easy.
Im in the same position as the 4S though, as in i have the iPad1 (had the 3GS before the 4S) so worth while for me. If you just web browse, watch films then probably not worth an upgrade to be honest, you might as well have an iPad1 if thats the case