... is out. OK, except it's not, because it's not shipping until the end of April, but at least Samsung announced a ship date.
Let me start by saying that Android is growing on me. I have a Nexus 4, and in general, I like it. It's not my day to day phone, but it could be at a push. Unlike the Nexus 7, I don't actively avoid using it. The OS - with 4.1/4.2 - no longer makes me want to hurt animate objects.
From a development point of view, there are some things in Android - even the old versions - that I much prefer over iOS, like the layout engine. I'd love a mix of both.
This is about as far away from my view of Android last year as it's possible to get. It's come a long way (baby).
This bit of the iMore review sticks out for me:
The Galaxy S4 hardware is a feat of engineering. It manages, in the same footprint as last year's Galaxy S3, to pack in a 5-inch 1080p display, massive 2600mAh (user-swappable) battery, SD-card storage expansion, and additional sensors like IR for entertainment console control, and temperature and humidity sensors. Unfortunately, the display is still OLED-based, and the casing still Hasbro-style plastic. If you hold a Galaxy S4 in one hand and an HTC One or iPhone 5 in the other, the difference in material quality is stupefying.
I had a SGS3 on loan for some testing last weekend, as it had a strange bug that wasn't showing up on the Nexus 4. I took the opportunity to have a good play with it, within the constraints of having to reset the phone back to factory by monday morning.
The OS is fine. I find the Samsung UI changes to look childish and "fisher price", like Windows XP looks now against Windows 7. In contrast, I like the HTC Sense changes and the stock Android look. None of them are perfect, but they are not ugly. The Samsung one just feels inconsistent - or rather, I find the consistencies to be jaring.
The physical build of the phone is my main issue. The iPhone 4S, 5 and Nexus 4 all feel solid in my hand. I'm not going to slip and drop it, or put it in my pocket and break it. And if I did drop it, it's not going to break more than a slight scratch.
The SGS3 feels like it would crack if I put it in my front pocket, and sat down accidentally. It just feels brittle and lightly built.
Not something you want in a phone.
By the same token, the screen is huge, and even with my fairly large hands, I have to use two hands to do anything more than basic functions. The Nexus 4 is the same, so I guess I just don't like 4.7 inch phones. Contrast that with the iPhone 5 which I can use with one hand with no issues.
On the flip side of this, the iPhone 5 feels like a toy now - more so with the 4S - but strangely, it still shows the same amount of data. Rod Drury had a good post on this effect when he got a Lumia 920. I find the same with the big Android phones, just not to the same extreme as with Windows Phone.
From the look of it, the SGS4 is the same. Same materials, same size, slightly larger screen, same weight etc. So, I'm going to assume that I'd like it about as much - which is very little. But I'm going to try one if I can get my hands on one without spending £600. Like pokemon, gotta try them all.
I suspect that Samsung will sell a boat load of these, like they did with the SGS3. At the moment, they are selling 1 for every 2 iPhones Apple sells. I'd expect this to be closer to 1:1 ot 1.5:1 by the end of the year. But really, it's now a 2 horse race: Apple, and Samsung. Which isn't good for consumers. It is great for cross-platform mobile developers like me tho - and indeed, anyone using the Xamarin toolset, or an equivalent tool.
 There isn't an equivalent tool......