Polycarbonate is alot stronger and more resistant than normal plastic, it may look similar but it isn't.

HTC One:

Same resolution, slightly higher PPI. But far lower contrast.
Same amount of Ram
Horrible primary camera, 4MP vs 13MP
Decent CPU but not nearly as good as the S4s
Horrible GPU
2300mAh battery vs 2600mAh and it's non removable (being that it is a li-on type, you better hope it never runs out of power cause the phone will become a worthless paperweight)

Xperia Z:

Same resolution, same PPI, But again far lower contrast.
Same amount of Ram
Storage only upgradable to 32GB vs 64GB
Slightly better primary camera, 13.1MP
Decent CPU
Same horrible GPU of the HTC One
2330mAh battery, again non removable.

Closer than the HTC, nearly as good in most area's and slightly better in a couple but also a couple of major downsides.

Lumia, Assume newest 920?

1280x768 resolution, 332PPI vs S4s 441PPI, IPS screen type = Horrible contrast and sharpness.
Only 1GB ram
8MP Primary camera
Horrible CPU
Horrible GPU
No FM Tuner
2000mAh battery, Non removable

Entry level phone, not even close to the S4 in any way.

Samsung showed almost exactly whats been rumored for the past month or so (other than the physical design) and it is very much an upgrade over the S3.

BTW, The polycarbonate case is actually used for a reason and while may not feel or look as good as an aluminum case, it is actually better as it is significantly lighter while retaining nearly the same scratch and impact resistance.

I love the Samsung design. I have no problem keeping the Polycarbonate plastic. It's light and feels great.

As for the whole being submerged underwater crap I have never used my S3 underwater, pretty sure I won't be needing to submerge my S4.

As for durability, I see a heck of a lot more broken iphone's in shops then I do any other phone on the market.

@Game

No it's not...durability is not why the average consumer buys high end phones...WTF

Bro we buy these phones for the seamless feature integration and easy UI it's just that simple.

Samsung again took the tech bumped it up a good amount but added a vast array of new features making functions that are on all phones a shit ton more simple.

You fail son...epic fail.

The batter is 2600mAh which is better than any other smart phone on the market, it is also one of the few that is removable.

The S3s is 2300mAh which at the time of its release was also the best on the market, and still is better than alot of others while again being one of the few which is removable.

The CPU was a bit of a power hog on the S3 though and android has always been needy also which is why it ran out fast, nothing to do with the actual battery.

Although i would still rather have a lower cap batter that is removable vs a higher cap one that is built-in. Atleast i wont have to drop another $600 for a new phone every time i accidently let the battery reach 0% charge.

Using both a Li-on type battery pack and having it Non-removable is a major design flaw imo. And i will never buy any device that does it.

I love the look of the S4. I dont like the square look of other phones.

They're on my Galaxy S 2 also, it's for sound.