Hold on to your touch screens. The first serious competitor to Apple's iPad has arrived.

The Samsung Galaxy Tab is a 7-inch touch-screen tablet computer that runs on Google's Android operating system. The model with 3G connectivity and Wi-Fi had a staggered release, starting at T-Mobile ($399.99 after rebate and contract, $599.99 without contract), at Verizon ($599.99, no contract option) and, finally, at Sprint ($399.99 after rebate and contract). All three carriers have different monthly data plans, ranging from $20 per month (1 GB on Verizon) to $60 per month (5 GB on Sprint). AT&T has yet to announce a release date for its version.

After briefly testing the Verizon model, my first impression can be summed up in a sentence: It's a giant Android smart phone that doesn't make phone calls.

No, really. The media used to joke about this with the Apple's iPad (which actually does offer a broader experience than iPhone). But the Galaxy Tab really does have everything in a smart phone except a calling plan. It even has a phone number assigned to it, but that's only for sending and receiving text messages.

It also offers a front-facing camera and microphone, which give it the capability for video messaging, plus a 3-megapixel camera and video recorder on the back with a flash and the ability to take panorama shots.

Here's a quick rundown:

Size: Unlike the iPad, this is much easier to hold in one hand. (The size works well as an eBook reader - a plus if you'll use it to download books from Amazon's Kindle app, but not so great for programmers who want to use it to publish electronic versions of magazines, since the smaller screen limits creative page layout options. The Tab is ever-so-slightly thinner than the iPad at 0.47-inches and weighs 0.84 pounds.

Display: Great touch screen response. The Samsung Galaxy S line of smart phones has an ultra-bright screen called Super AMOLED. The Galaxy Tab doesn't share the same saturated color screen technology; it's a LCD screen, but it's nothing to complain about.

The interface is practically identical to the typical Android phone interface, with a few changes such as calendar and contacts, designed to look like planners to take advantage of the screen real estate.

Apps: It's equipped with the Samsung Media Hub, where you can rent and buy movies and TV shows. (But it sure would be nice to have something to prop it up.) But in the battle against Apple, the Tab falls way behind. When the iPad launched, it offered a ton of apps made specifically for the iPad's large screen. On the Tab, you're getting the same apps as you would from a phone. Most of the popular ones will just expand larger, but many stay small, leaving a black border around the app. Until Android comes out with an update to fix this, users have to fiddle with a third-party app called Spare Parts to reprogram the settings.

Battery: Samsung dropped the ball with the charger. You can only charge it from a wall, not from connecting it to a computer. But the battery life is pretty good.

Connectivity: Using the carrier's 3G speeds, it can serve as a mobile Wi-Fi hotspot, giving Internet access to nearby gadgets.

Bottom line: The Galaxy Tab is a great gadget for portable computing, but when you realize it does (nearly) everything an Android smart phone can do, the price tag feels pretty steep for someone who already has the latest smart phone. I'd like to wait and see what apps are made to take advantage of the larger screen. If the 3G data plan isn't your style, you'll have to wait until next year for cheaper version that only uses Wi-Fi.