I too had a S2 and I can tell you that the S5 is better overall.
The only thing that S3 has over the S5 is the built in codecs out of the box.
So while basically every multimedia file you throw at the S2 plays out of the box, with the S5 you may have to get the file in a different format or get a third party media player. Other than that I preferred the S2 camera somewhat.
To me the overall pictures are sharper with the S5. There is no sharpness adjustment feature on the S5 like you get with the S5. Don’t get me wrong, the S5 has an amazing camera and you may even consider the S5 camera to be better in clarity in comparison to the S2. The best thing for you to do is compare them yourself and be your own judge.