he svelte Samsung’s Galaxy S platform comes to U.S. shores with an amazing 4-inch Super AMOLED display.

Seeing Samsung’s new Galaxy S hardware on a web site just doesn’t do it justice.  You have to pick one up to just feel how light they are and how beautiful the four-inch display looks almost better than reality.  I’ve been using both the T-Mobile Vibrant and AT&T Captivate for the past week and have to say it will be hard parting with them.  The Vibrant went on sale this week and AT&T’s (T) Captivate hits stores today.

Except for the encasement design and 3G radio hardware, these two phones are pretty much the same device, so I’m going to group them together unless otherwise specified.

I’ll start with the good and work my way down to the issues…

This is the best screen I’ve seen on a phone, period.  That’s coming from someone who has been using an iPhone 4’s Retina Display for the past few weeks.  Sure there are more pixels on the iPhone 4 (most of which I can’t see) but the Galaxy’s much larger four-inch, Super AMOLED display more than makes up for the lacking pixels.   If you have any doubts, check out the Avatar video that T-Mobile includes with their phone. Not one person I’ve shown this to hasn’t been blown away (expletives abound).

The viewing angles are also the best I’ve ever seen, which make sharing videos doable (unfortunately, it also helps your neighbors in the train see what you are doing as well). Viewing angles in sunlight aren’t as hot but looking straight on, like you’d do 99% of the time, it is as good as high end IPS LCDs (like EVO/Droid/iPhone).

A knock on traditional AMOLED displays, like that of the Nexus One, has been its performance in sunlight. This ‘super’ version built by Samsung is just as viewable in sunlight as LCDs like those on the EVO, Aria or even the iPhone.  What’s even more astounding is that Super AMOLED’s blacks are perfect in the sense that there is literally no light emitted. Samsung says this screen also saves power and allows the Galaxy S to be thinner and lighter. The Amazon (AMZN) Kindle app takes advantage of this by using a special white text/black background mode that uses almost no battery — almost like eInk.

The trend in high-end Androids has been “up-up-up”, both in size and weight.  It is refreshing to see hardware that goes the other direction in thickness and weight, while retaining a super-sized screen.

Both of these devices weigh in at 117.9 grams or 4.16 ounces . That’s a whopping 20 grams (14%) less than the iPhone 4’s glass-backed and steel-framed 4.8 ounces (137 grams)  — which is even more astounding when you consider the Galaxies have a much bigger screen. Oh, and that’s without the bumper.

In fact, the Galaxy S is only a few grams heavier than the much smaller-screened HTC Aria from AT&T. While I am a big fan of the Aria (and it can be had for free with a plan), it is time to say good-bye to that recommendation for small, free-with-plan Android devices (see prices below).

No other high-end Androids come close to the weight of this thing. The EVO (170G) and Droid X (155G) feel like anchors in comparison.

here are significant external design differences between the Vibrant and the Captivate. The Vibrant looks like a thinner, lighter — but also bigger —  iPhone 3GS, while the Captivate’s edges are more square.  I personally prefer the Vibrant by a small margin, but this is subjective.  Both feel great in your pocket; the size to weight ratio makes it feel like the battery fell out — it is unnaturally light (a good thing).  You will wonder how a device with a an amazing four-inch display can be so light.

These devices are also as thin as you’ll find on any Android phone at 9.9 millimeters. While the iPhone 4 is less than half a millimeter thinner, the bumper makes it a thicker package than either Galaxy overall.  The Galaxy feels thinner in your pocket because of the rounded edges and curved back.

While I’m normally a huge fan of Apple design, I really don’t like the way the squared-edged steel and glass iPhone 4 feels in my pocket or in my hand.  I much prefer the rounded, soft  iPhone 3GS-type plastic that the Galaxies have.  This is something you need to try for yourself as everyone has a different taste on this.

The camera on the Galaxy S is 5 megapixels and it has no flash. It also has no front-side camera for video chatting (the European and Sprint Galaxy S models do). That being said, the camera performs really well, especially in low light conditions. It has manual and automatic ISO settings like you’d find on a Samsung point and shoot and a bunch of other consumer camera features. In normal conditions, the still images are fantastic and as good as the iPhone 4’s, at least to my eyes.

The software is Samsung’s own and takes a few minutes to get used to but works fine overall.

The camera also takes 720P video but the quality isn’t nearly as good as a Flip phone or the iPhone 4 (which might be due to compression). There is also no HDMI video out on this phone to watch your videos, but I’d almost say that watching videos on the Galaxy’s screen is as enjoyable as the big screen.

This is the fastest gaming Android device available.  Here’s a benchmarking video from Android and Me demonstrating the capabilities of the PowerVR SGX540 (which is double the speed of the current generation PowerVR SGX530 GPU of high end Android devices and the SGX 535 of the iPhone’s A4).