To say that Research in Motion's BlackBerry PlayBook is a study in contrasts is an understatement. After extensively testing a PlayBook that was running not-quite-final software, I'm impressed by its convenient size and novel navigation, but I found the tablet's sometimes primitive native software and selection of apps frustrating.

In some respects, the PlayBook is the most impressive tablet I've seen to date. Its approach to navigating among open apps is a joy, and I was able to move among them faster than on any other tablet. But native apps like the PlayBook's browser have disappointing glitches, and you won't get much help from downloading third party apps. Only 3000 will be available at launch (compared with the 65,000 available for the iPad), and I still haven't seen many marquee names among them.

The first thing you'll notice about the PlayBook is that it's compact and light. Like the Samsung Galaxy Tab, the PlayBook has a 7-inch display, significantly smaller than the 9.7-inch iPad 2. At 7.6 inches wide, 5.1 inches high and just 0.4 inches thick, the PlayBook is small enough to comfortably fit into a generous coat pocket, and yet provides enough screen real estate to feel like a significant improvement over a standard smartphone screen. Its depth falls smack in between the Galaxy Tab and the iPad 2, at 0.1 inch thinner than the Galaxy Tab, and only 0.06 inch thicker than the svelte iPad 2.

And its weight? Just under 1 pound (exactly 0.94 pounds, according to the lab scale), which makes it 28 percent lighter than the 1.3-pound iPad 2. By comparison with other tablets I've used, the PlayBook felt downright featherweight. It was by far the easiest to hold, whether you use two hands or one. The PlayBook feels solidly built, with a velvety-smooth, textured back. I do wish the edges were more rounded (they are squared and angular), but that didn't bother me too much.

While you can use the PlayBook in portrait mode, it's designed to work best when held horizontally. In that landscape orientation, the PlayBook's 3-megapixel front-facing camera sits centered over the top of the screen, with several buttons flush along the edge: the power button (which is miniscule, stiff, and difficult to use), volume buttons, and a mute button that doubles as a play/pause button. At back, centred along the top edge, sits the 5-megapixel camera (which has no flash). The stereo speakers are front-facing, and centred at either side of the screen. My smallish hands never came close to blocking the speakers, though those with large hands might have a different experience. The audio output from the PlayBook's speakers is the best I've heard yet from a tablet.

Along the bottom of the tablet are three ports: HDMI Micro, microUSB and a magnetic rapid charger connection. The PlayBook has three different charging options: slow, fast and really fast. Unlike most tablets, the PlayBook can charge fully off of a standard PC USB port (at 5V and 500mA), but it'll take a while. The process goes almost four times more quickly, according to RIM, if you use the included microUSB wall charger. If that's not fast enough, you can spring for either of two options: the Rapid Charging Pod or the Rapid Travel Charger. The rapid charging options rejuvenate the PlayBook battery nearly twice as fast as the wall charger, RIM says.

Inside the PlayBook, you'll find a competitive set of components. The tablet is powered by a 1GHz dual-core processor and 1GB of memory. This initial iteration connects to 802.11 a/b/g/n Wi-Fi, but lacks any mobile broadband connection. For that, you'll have to wait until late summer, when RIM will release 4G LTE and WiMax versions of the PlayBook. The unit I tested came with 32GB of onboard storage and as mentioned, it is also available in 16GB and 64GB. You'll need to choose your capacity carefully since, like the Apple iPad, the PlayBook has no memory expansion card slot.

Interface and multitasking

The PlayBook runs RIM's new BlackBerry Tablet OS, based on software from RIM subsidiary QNX, which builds operating systems for everything from in-dash car appliances to electric guitars. This OS has a fresh look and feel, and its touchscreen navigation concepts are novel and innovative, albeit it with a few bumps.

Let's start with the basic navigation. The PlayBook has no home button. Instead, touch controls are integrated into the bezel, and you navigate about with swipes that originate outside the screen, or move down or up towards the bezel.

The gestures work differently depending on the context. For example, if the PlayBook is asleep, you can wake it by swiping up from the bottom bezel into the screen. Once you're on the home screen, a swipe up will reveal a screenful of app icons. If you're in an app, swiping up will close the program.

The PlayBook's home screen is divided into three components. A narrow status bar up top, a large horizontal navigation pane in the centre that shows thumbnail images of your open apps and along the bottom the first row of the app menus. These menus are by default divided into folders: All, Favorites, Media and Games. The status bar at top gives one tap access to Bluetooth, Wi-Fi, battery life percentage and general settings info.

Within the navigation pane, you can swipe from side to side to move among open apps, an easy way to switch among tasks. When you're not on the home screen, you can always reveal the status bar by swiping down from the corners. And when you're in an app that uses the keyboard, you can swipe up from the bottom bezel to reveal the keyboard.

While it sounds complex, the navigation system is intuitive and quickly becomes second nature. The PlayBook is also responsive: Screens refresh quickly, and transitions and scrolling are snappy. On the whole, RIM has come up with a simple and elegant approach to navigation that is easier and more flexible than the iPad 2's iOS 4.3. One thing I miss: the active widgets on Android 3.0 that keep you updated with bits of information without having to open an app.

Individual apps sometimes have additional menu options that can be revealed by dragging up or down from the bezel. The problem is that those options aren't always obvious. Built-in apps like the web browser, the music player and the video player have no visual cues alerting you to additional menus or navigation options. It was only through experimentation, for instance, that I found that if you swipe down from the top bezel, you'll see a convenient horizontal scroll of thumbnails of your videos, so you can easily hop to another selection in your library.

The BlackBerry's notifications are unobtrusive: Messages appear in the upper right corner to tell you that the battery is running low, for instance.