My short review of S4 (i9500), coming from Note 2 after one week of usage.
I have been thinking for quite some time to change to S4 from Note 2 or not since couple of weeks, but decide to change it since I already have iPad Mini, no point for me to carry two big screen devices at same time.

1. Screen: The screen is fabulous! I think this is the best mobile screen I ever saw, besting up even HTC One. I do have to adjust to the smaller screen size compared to Note 2 last time, but the funny thing is since everywhere ppl are using Note 2, I found it to be super huge especially when I saw petite person using it. (I do miss the huge screen size of Note 2 tho).

2. Camera: Miles better than any of smartphones I used before. Now I can safely leave my dslr at home since I'm not doing any professional wedding works anymore.

3. Battery: Note 2 is hands down winner here, but I changed the stock battery to Sun Global's 3100mAh, so far so good but the cons is I lost my NFC capability.

4. Lag or bugs: Changed the rom to OmegaROM, so far all smooth sailing and never have any camera app crash (except when using stock rom early on). I can say it perform better than Note 2 especially on gaming.

5. Disk space: Coming from 32gb Note 2, I have to say its pretty irritating early on of having only 8gb usable space. However after applying some tips now I manage to get used to it. The tips are:
- Big size games installation: thanks to JayceeOoi tips, now I'm using Foldermount.. app to move the game's data folder to external sd card.
- Gmail: Using Diskusage.. reveals that my Gmail app's cache took up 1.5gb space for my three gmail accounts. So I reduce the "Days of mail to sync" to 10 days and disable auto download attachements on wifi.
Now after installation of couple of games (Real Racing 3, Anomaly Korea, Kingdom Rush, CSR Racing and of course Candy Crush), I still have 6gb usable space with extra 32gb ext storage.

Overall i'm satisfied using S4, altho not as sexy as HTC One or not having front faced stereo speakers, I will stick with this phone until Note 3