At first I also have the same problem as you, i think it is because of the major transition of a4 chip of iphone 4 into dual-core a5 chip of the iphone 4s. The battery cannot keep up with the performance of the dual-core and graphics of the 4s. Although you cannot dramatically improve the life on your iphone 4s, you can get noticeable changes by doing this things:
1. Limit the use of high-end games on your iphone.
2. If you can, switch from Wi-Fi instead of 3g it gives you approximately 1-2 hours more battery use.
3. Turn off cellular data, location services, wifi and 3g if not in use. (very important)
4. Organize your apps into folders by category (having apps readily opened in the home screen sucks up battery)
5. Put your volume at it's lowest when not in use or on average when your using it.
6. Turn on airplane mode when your planning to use your iphone on a remote/low-signal area).
7. Use the sleep/wake button (don't just wait for the screen of the iphone to turn off by itself)
8. Use earphones instead of the built-in speakers
9. Watch/Observe the temperature of you iphone (when charging place it on a flat stable cool location)
10. When using apps and you notice your iphone to be kinda warm, take a break and use it later. (Having a warm/hot-like iphone drains more battery)
11. Lower the screen brightness to the lowest without straining your eye.
12. Turn off Siri
13. Organize apps that use Notification Center
14. Turn off Fetch new data in mail.
15. Turn off automatic downloads of Itunes and app store.
By doing this things you can maximize the battery on your iphone 4s. As far as improving the battery life when using 3g, apple says the iphone 4s have 6hours at max, in my experience at max I only get 5 hours from 100%-0% using 3g. We can do nothing about that.tch!
About the charging time of your iphone 4s, i think that is normal because from 0% to 80% it undergoes fast-charging then from 80%-100% the charging time slows down to ensure that the battery is really full which is called continuation phase. You may notice that even though it is already 100% you may see the lightning bolt sign which indicates that it is still charing, it is because your battery is still not fully calibrated. Allow 15 minutes or so then the battery sign will change to full. Also calibrate your iphone once a month so the reading it gives will be accurate.
From my experience the 4s is by far, have the worst battery, I charge it for like once everyday but a change of lifestyle can change that all. I hope it helps! :)