Nobody has been able to match the iPad thus far. But the PlayBook, the first effort from BlackBerry smartphone maker Research In Motion, has emerged as one of the strongest contenders.

On the surface, the PlayBook looks similar to other iPad competitors: Its slick touch screen measures 7 inches diagonally, smaller than the iPad’s but comparable with those of others. It has front and rear cameras for snapping photos and video conferencing and a black rubberized plastic back and sides.

What’s different is the software powering the PlayBook. Most non-iPad tablets use Google’s Android software; RIM developed its own — a smart decision, yielding a device that is a pleasure to navigate and filled with cool features. Although RIM’s software was built from scratch, it has hints of the BlackBerry phone’s interface.

When it goes on sale on Tuesday, the cheapest version will cost $499 — the same as the cheapest iPad. It comes with Wi-Fi capabilities and 16 gigabytes of memory. A model with 32 GB will cost $599, and the 64 GB version will go for $699. Sprint plans a version that works over cellular connections this summer, rivaling the ability of different iPad models to connect to the Verizon or AT&T network.

Unfortunately, the PlayBook isn’t yet much of a competitor on the app front: There are just 3,000 applications currently optimized for the tablet, and during my testing it appeared unable to download App World apps available for BlackBerry smartphones.

By contrast, there are more than 65,000 apps available for the iPad, which can also run iPhone apps (Apple offers more than 350,000 apps total). And while it’s unclear exactly how many tablet-specific Apps there are for Android, Android tablets can run any of the more than 150,000 apps in the Android Market.

But the PlayBook aims to catch up, in a way: Later this year, it will be able to run Android apps, too.

In my hands, the PlayBook felt solid and easy to use. There are just a few buttons on the top for adjusting volume and playing or pausing music or videos. There’s also a tiny button for turning on the device — so teeny, in fact, that I regretted trimming my nails right before testing.

Finding my way around the PlayBook was delightfully easy and fast because it has a speedy processor.

At the top of the main page sit device settings and alerts for things such as software updates. Across the bottom, you see a scroll of apps that you can swipe through or expand to fill the screen by swiping a finger upward.

In the middle of the screen are small thumbnails of your open apps; you can slide your finger left or right to sort through these and pick or dismiss them with a tap or a flick.

One cool feature: Open apps remain active even when you’re looking at them from this view. So if you open the camera and later sort through your open apps, the viewfinder will still be working in the tiny thumbnail of the camera app.

Even though the PlayBook is smaller than the iPad, its screen was bright, colors looked rich and images were sharp. I felt immersed watching videos — a combination of the excellent display and simple frame surrounding.

The PlayBook supports Flash video playback — something the iPad doesn’t do — and HTML5 for rich video content. Thus, you can browse the Web much the way you do on a computer. There are a few annoying quirks: For example, the PlayBook took a long time when scrolling through long documents or Web pages.

In general, though, the PlayBook’s screen was very touch sensitive, and I especially liked how the PlayBook takes advantage of it. Instead of hitting the power button to wake up the device, you can make one long swipe upward with a finger.

When using an application, a long upward swipe will bring you back to the main page that shows the settings and your applications. Make a hard swipe to the left or right to flip through your other open applications. Another neat trick: You can zoom in on Flash videos by spreading two fingers on the screen.

Like so many other tablets, the PlayBook includes cameras for taking photos and videos and for video chatting. On the rear, the PlayBook sports a pretty simple 5-megapixel camera that took decent photos (no flash, though) and videos. The 3-megapixel front camera is probably more suited to video calls. I wasn’t able to try it, though, as RIM isn’t planning to roll out a video chat app until after the device is available.

Of course, RIM is known for its focus on business users, and the PlayBook can do plenty of work, too. It includes word processing, spreadsheet and slideshow apps and can easily be attached to an HD TV through its Micro HDMI port (for presentations or, if you’re like me, streaming online movies to a flat screen). Its onscreen virtual keyboard was surprisingly accurate and took very little time to get used to.

And if you have a BlackBerry phone, a nifty feature called BlackBerry Bridge links the two devices over Bluetooth. When I tested it, it wasn’t fully functional. But it promises to let you easily do things on the tablet such as using the BlackBerry Messenger app on your phone and accessing BlackBerry e-mails and calendar. For a business user who feels constrained by the BlackBerry’s small screen, this could be a nice complement.

RIM expects the PlayBook to get eight to 10 hours of battery life while multitasking. I got about six hours while surfing the Web, streaming Internet radio, checking e-mails and streaming videos. Maybe this was actually a hint that I should limit my music video habit.

The PlayBook is an impressive tablet — it has to be, considering the iPad’s head start. And if RIM can ramp up its app offerings, it will be an even heartier contender.