Yes but the Iphone 5 now has :
Same size increase in screen size ( 0.5 inches , Same PPI as the S3 )
A much more powerful Processor then the 4S and possibly S3
Improvements made to this camera in both software and hardware
It has a new design , it may not be completely different but it is still different from the 4S cosmetically as well as size , thinness and weight.
Improved battery life over the 4S
New OS and new software / apps
Now has New wifi 5ghz , LTE , new microphones , headphones , connectors
As far as i can tell there are just as many changes if not more then the S2 to S3 jump.
Screen size is 2 years out of date.
Processor upgrade a waste of time, the phone is strangled by iOS6 that a 4 or 4s can run, so its capacity isn't going to get used.
iOS6 was a disappointment when announced, its very light on new features
So they made it a bit thinner and lighter by dumping the glass BFD.
Connector is hardly a "good" upgrade for the customer, the adapter to re-use your old accessories is $29, so probably £30 here.
LTE a waste of time, its exclusive to Everything Everywhere until 2014, will be expensive and more than likely have iffy coverage (like HSDPA but worse).
Other than bragging rights there is little point getting a 5 over a 4s.
Also as far as the S3 goes it added a stack of software features like S Beam, smart stay, share shot, a whole bunch of gesture controls, smart alert etc
Each on their own are only small things but added together they do make an impact (imho).