I'm coming from an S2 aswell like the OP, can't wait, so glad the release is close to the announcement.
The S4 was a straight up disappointment and although I'd prefer not to have a huge phone, it's got everything else right, including snapdragon 800, a new, bigger camera that does 1080p @ 60fps- about freaking time. I guess I'll fool around with 4k aswell.
The battery could have been bigger but I'll get a 2nd anyway, it has 600 more mAh over the S4 and only .7 of an inch more screen panel, so I don't think it'll be a problem.
Looking forward to using the stylus and that fab-sounding search function, so I can find a music track easily without travelling through folders- I prefer not to use the built in music app of the phones I've had, but it has become a bit of a chore over time.
My S2 has actually been broken since December and my old phone I went back to (LG Renoir) has a stylus, although it's more of a 'flavor adding' feature and didn't need one, ah the early days (stylus for a 2.8 inch screen...lol).
I told LG to make a new Renoir to rival the note/5 inch phones (and bring the artsy vibe back with it) but as you can see nothing happened.