S4 here, it’s a phone, does phone stuff well (actualy very well, coming from a dumb-phone I was amazed how clear calls are). Screen is ace compared to my missus S2, apps are nice to have, lots of guff pre-installed though, to the extent I’m tempted to go through the whole hack/re-itall.
Can’t comment on speed as I’ve not got another phone to compare it against, but it’s not slow loading stuff.
It has pretty much replaced my laptop for general internet stuff, so don’t underestimate how good the quality of the screen needs to be, the S2 drives me nuts.
Only criticisms are: It seems to need re-setting every so often as it just loses signal completely (or sometimes jut the data portion of it). But my old phone used to do that too so maybe that’s T-mobiles fault? And the screen is a smidge too big, so it’s more hold in one hand and navigate with the other, whereas the ‘mini’ or iPhone sized phones you can use one handed. Samsung seem to have aproached it as the smallest practical tablet you can fit in a pocket, rather than keeping phone ergonomics.
There’s an S4 outdoors/active version now, I loked at it but it was new so £10 a month more so I discounted it, £240 more over 24 months would probably buy me a new S4 if it get’s trashed once the S5 comes out.
As for dropping/cases/glass, I bought a wallet styule leather case for about £20, holds the phone, couple of cards and some folded notes. It’s not tough int he armoured sense, but it’s soft enough to absorb impacts, fallen out my pocket before on the bike without drama. Only thing I wory about is sweat getting into the camera whilst it’s in my jersey pockets, I bought a waterproof case but it’s bulky and a faff to swap cases before every ride.