4S is great. It's (cpu) is powerful enough, has the 8MP camera as the 5 does, and the photos are quite good.
Failing that... just hold back and see what the 5S offers when it comes out.
Personally I went from a 4 to a 4S. I wanted a better camera mainly. I panned the 5 because I couldn't justify the cost of another 2 year contract for hardware which quite frankly, is not that much better than the 4S.
- I didn't feel that an extra row of apps (longer screen size) was of any worth.
- Couple of millimetres thinner? So what.
- LTE/4G? Don't need it. On 3G I get @5Mbps, that's plenty fast. Even for tethering to my laptop for general net use.
- I also prefer the glass back to the aluminium back.
I use my phone to make calls (surprise), use email, take photos, and I use some apps like TomTom, Google Maps and Runkeeper.
I don't play games on it, so CPU is not an issue. CPU has more than enough horsepower.
4S meets every requirement in my situation, and I'm saving at least $500 a year compared to upgrading to a 5 because now I'm on a pre-paid, unlimited plan, no contract. I paid $500 for the phone, and it's on it's way to paying for itself.
If the 5S does not offer much, I'll stick with the 4S -
- or maybe,

go to another brand.
.