Another plasticky phone, I believe a top end offering like S4 deserves better building materials. Apart from 'misleading' Octa core moniker (since only one of the two quad core SoC will be operating at any given time), and gimmicky features, there is nothing really exciting especially for those with S3.
I think HTC One is overall much better package, and somehow, Sense 5 seems to be whole lot less messier than TW. Add that to a much more practical size of 4.7", and 32GB storage out of the box, it is lot more compelling choice. But unfortunately, I ain't buying another android any time soon, since, I got a 920 to go with S3 (which admittedly I use a lot less these days, mostly for experimentation with custom ROMs).