In my view yes. Have you looked at “3” as a provider as contracts are attractive (£30 for iPhone 5 plus £30 a month), it does depend on network coverage for your area though.
The larger screen is useful – I read a lot of online content, newspapers etc, and in landscape mode the extra 1cm or so makes a difference.
Its much lighter which I prefer, many people don’t like the lighter phone as they say it’s “toy like” as above – so personal taste.
5 has other improvements such as better camera
The 4S is still a good phone, its what I have. It has the panorama camera, SIRI etc. When the next iPhone comes out (October ?) the 4S could well be dropped and in any case ahead of the new iPhone it will be heavily discounted and/or free.
When iOS 7 comes out in Autumn (and it will run on 4S and 5) it will contain many improvements inc software changes meaning better battery life
Like most long time iPhone users I have many cables but the new lightening ones are £15 for the Apple originals so buying an extra/spare isn’t a crises and the USB plugs are still the same.