Is it worth upgrading from a 4S to a 5?
If I can point to any single factor in your decision, it is LTE. If you are in an area with good LTE support, and the extra speed is valuable enough to you to justify an early upgrade, then by all means upgrade.
Other than that, the rest is fairly minor, all things considered. Thinner, lighter, faster.
Keep in mind that the extra speed is of no real benefit yet - there aren't any apps which use it, unless you are doing processor-heavy work already, such as video, photo, or audio work. These things will definitely run faster, but is that enough to justify an early upgrade? Probably not.
If you watch a lot of widescreen video on your phone, the new screen is a big improvement. That extra half-inch makes for a significantly larger picture, since you use more of the screen (less or no letter-boxing).
I agree that the biggest benefit right now is LTE and wow it is fast. If you're on ATT with your 4S you already have 4G (HSPA+) and LTE is faster but it's probably not worth the step up considering the cost. If you have Verizon though, you are still on 3G and so the LTE will be a bigger difference, though you still can't talk and surf at the same time.
If you can find a buyer for your 4S and essentially make the switch with paying less than $100 I say you should definitely do it, since you love Apple products and you probably think about getting the 5 over 100 times during the day. If you want to keep your 4S I don't think shelling out $500 is a good idea in this case.
If you were you, see how much you can get for your 4S and go from there. In the meantime, back it up to your computer so if you have to sell it on short notice you can and just swing by the Apple/Verizon/ATT store later that day to get your new phone.
For just a quick review of the 5 my only gripe is getting used to the headphone jack being on the bottom. Other than that, it's better in every way. Bigger, but less glass so it's actually more durable. The thinness is really noticeable and everything else is minor upgrades, but still upgrades. Since I just got it, I really haven't been able to test out the battery life, but syncing takes a fraction of the time and the new processor speeds up all the first party apps in the noticeable way. The new headphones are cool, but just another minor upgrade.
how do you use your device now? for me the phone has become a secondary device to my iPad 3 with 4G. the iPad has become my go to device and the phone is really just used for taking calls and texting.
i will admit i have been really really really tempted to go down and get the phone this is the 1st iPhone i have not upgraded to but i just don’t use the phone like i used to now that i have the iPad.
other than speed, extra screen real-estate, better camera lenses and the thinner design iPhone 5 really doesn’t offer anything that the iPhone 4s doesn't have. With iOS 6 the 4S has all the same software features that the the 5 has.
good luck on holding out and not getting the phone. i think if you can hold out for the next few weeks you will be fine. Also if Apple does release a new “iPad Mini” this fall that should help diminish the hype machine around the iPhone because they will be now focused on the new apple hotness.