I was using iPhone 5 (my first iPhone ever) for almost a year, but due to job changes, I had to buy a personal phone and I ended up with iPhone 4S (used) Due to the upcoming announcement, I did not feel like spending close to $700 made any sense on 1 year old technology.
Spec & performance aside, I actually like iPhone 4S better then iPhone 5 - not sure if it is the shape, but it just fits better in my hands and feels more premium - personal opinion of course.
I am going to keep the iPhone 4S till the new phone is easily available for purchase and then I will make a determination if it is actually worth getting.
To answer your question, I think 4S still makes a lot of sense - especially if you are getting a used one - I think it is a great buy. Good luck