Let’s get one thing straight. The Dell Streak, due to be available from O2 in the U.K. and likely from AT&T in the U.S. sometime soon, is not an Android tablet PC, despite the company’s self-declaration of same, and is not a competitor to the iPad or an iPad killer.

I got my hands on a pre-production Streak prototype, and Dell’s more conventional Aero Android phone, for around a half-hour yesterday.

And now that I’ve held it and played with it, I can tell you the Streak is not a tablet, it’s just a really large cellphone. A nice cellphone, but still a cellphone.

Why isn’t the Streak a tablet? As Supreme Court Justice Potter Stewart once described his legal definition of pornography, I know it when I see it. Streak has a 5-inch 800 x 480 pixel screen, and that’s not large enough to be defined as a “PC,” tablet or otherwise. It walks like an Android cellphone and it talks, literally, like an Android cellphone. Ergo, it’s a cellphone.

Streak Features & Design

The Dell Streak is designed to be held in portrait mode – when you hold the Streak in its OS default landscape view, like a tablet, the now-familiar Android Home, Menu and Back buttons are stacked vertically on the side, unlike a tablet. When held in landscape, the Streak’s volume and on/off switch are on the top left perimeter, requiring an untablet-like reach-around to get to these oft-used controls.

As noted, Dell futzed with Android to produce its own home screen, which has a customizable row of frequently-used apps. The Streak even has cellphone specs. It runs Android 1.6 and, even though Dell designed its own customizable home screen, Android has never run anything other than a cellphone (unlike iPhone OS, which is a derivative of Apple’s desktop Mac OS).

The Streak has a 5 MP camera – a tablet is too clunky to be used as a camera – with dual LED flash. Even though it’s a quarter the size of the iPad, Streak still is a bit large for anyone used to a pocket-sized point-and-shoot digital camera. Its front-facing VGA camera (video chatting “coming soon”), positioned to be used in portrait mode like a cellphone rather than in landscape like a netbook/notebook camera. I could not tell from the press prose or specs if the Streak has a video recorder.

Streak also has only a non-tablet-like 512 MB of user accessible memory (there’s 2 GB dedicated to app storage), relying instead on a cellphone-like DIY microSD slot for store your data.

On a productivity level, there are thus far no Android word processing or presentation creation apps of any note (there are a couple of spreadsheet apps, but are you going to create a spreadsheet on a five-inch screen?), which means the Streak can’t really replace a netbook. But even if the Streak had word processing capabilities, there’s no room on even its 5-inch screen to type with two hands, much less touch type as you can on an iPad (or, at least attempt to touch type). This makes the Streak totally impractical as a prose creation device for anything beyond email and texting, and makes it a cellphone, not a tablet.

Externally, Streak’s display is protected by a sheet of tough Corning Gorilla Glass. At the event, the Dell rep pounded the screen with a pen top, and I mean pounded, producing not a hint of damage. Unfortunately, the rest of the Streak is made of lightweight plastic, so caveat klutzes.

At 3.1 inches wide, the Streak will fit, barely, in a shirt breast pocket, but only in sub-cargo pants pockets, not in side slit or back pockets. But at 6 inches high it could tip out of said pockets and, even at a surprisingly light 7.6 ounces (which, quite frankly, makes Streak feel a bit insubstantial), it’ll sag your blouse.

Phone Functionality

Don’t get me wrong: I actually liked the Streak – as a cellphone. Its 5-inch screen makes a great viewfinder for the 5 MP camera and camcorder, if it has one, and is the perfect compromise size for mobile Web surfing. Its touch scroll is nearly iPhone smooth and offers multi-touch for pinch-and-zooming.

For social networking, Twitter and Facebook are built-in with home screen update bubbles, and of course you get the usual Android email functions.

And, finally, the 5-inch screen creates a wonderfully large phone touch dialpad, although one-handed thumb dialing is difficult.

With 7.2 Mbps 3G connectivity, mobile Web pages loaded in a speedy 3-4 seconds.

The specs did not indicate what processor is powering the Streak, but other sources say it’s the 1 GHz Snapdragon chip cropping up on most new phones and tablets. But I still found the Streak slightly sluggish – but the test model I played with was a pre-production prototype, so benefit of the doubt and all that.

Battery Life

Streak’s got a hefty 1530 mAh battery, which likely accounts for most of its weight, but we’ll have to wait for a more formal review to determine real life battery life.