Is it iPhone 4S is better than iPhone 4?

Just wondering

Of course!

Of course, more advanced configuration, and one more siri feature

Yes definitely, no doubt in that

That depends on what you mean by better. The 4s is newer and in theory more expensive. Because you can still get a new 4s but all 4 will be used, a 4s is theoretically more reliable. However, if you're not buying with a contract and just need a stopgap phone for a year or so, you will have to buy w/o a contract and the initial outlay will be cheaper for a used iPhone 4 than a new (or not so new) 4s.

It is faster and has Siri. I have heard complaints about iOS 7 running slow on iPhone 4. You can always get a Android phone.