Everyone knows about the iPad. It's been a smash success in just about every consumer-electronics metric you can imagine: sales, adoption, app ecosystem. Apple seemingly cannot make them fast enough to keep up with the massive demand. While some have dubbed the iPad "just a big iPhone," the worldwide consensus, if sales are any indication, is that the iPad is a very big deal.

However, the iPad is certainly not the only player in the tablet computing sphere. Three major competitors have emerged: the Galaxy Tab, the Blackberry Playbook, and the Motorola Xoom. Are these tablets worth considering instead of an iPad? Or, if you want a tablet computer, should you just get an iPad?

Galaxy Tab

The first major iPad competitor, the Samsung Galaxy Tab is Android-based and is 7-inches. Most reviews of the Samsung Galaxy Tab are mixed. While it does some things well -- namely, syncing of contacts, calendars, and e-mail items with Google services -- its operating system was not optimized for the tablet layout. This is because it is running Android 2.3, not Android 3.0.

For users who want a smaller, more compact tablet, the Galaxy Tab may be worth a look. However, the small form factor may make it more difficult to type on than an iPad. Test out the Galaxy Tab before you buy one.

Blackberry Playbook

The Blackberry Playbook, while seemingly good on paper with specs such as 1 GB RAM and a 1 GHz processor, is an incomplete product. Many of the reviews of the Playbook, when it was released on April 19, 2011, likened it to a beta release that users have to pay for.

For example, the Playbook does not support e-mail right out of the box. Yes. That's right. The Blackberry Playbook, despite the fact that the original Blackberry was _built_ on strong e-mail support, does not support e-mail without being linked to a Blackberry. While Research in Motion (RIM) claims that they will release a software update to the Blackberry Playbook sometime in Summer 2011 that provides native e-mail support as well as calendar support, that may be too late for consumers.

The hardware of the Blackberry Playbook might be great, but without ample software, it cannot be recommended as an iPad competitor.

Motorola Xoom

The Motorola Xoom is the most complete iPad competitor. Its form factor is slightly different from the iPad, as its screen is a true 1280x800 pixel widescreen aspect ratio. While this makes the Xoom excellent for watching movies on, it does make holding the Xoom in portrait mode more challenging.

The dual core processor and 1 GB of RAM (compared to the iPad's 512 MB of RAM) mean that the Xoom can keep more processes open at a time. This can be a bit of a curse, though, as the iPad's battery life is greater than the Xoom's; the heavy CPU load of the Android 3.0 operating system might be affecting battery life.

The iPad is still the most polished and complete tablet computer. Those who want great alternatives to the iPad should wait at least six months; the iPad will likely remain peerless until at least the holiday season.