When Apple released the iPad 4 in March 2012, Apple CEO Tim Cook announced what he called a "post-PC world," and Apple's place in it. He makes a good point: Tablet sales are catching up to laptop sales and have been for a few years. Research from Gartner suggests that PC sales - both laptops and desktops - will decline by another 10 percent in 2013, while tablet shipments will increase by more 67 percent. Sounds pretty convincing, right?

What's less often discussed is why tablet sales are growing and who's buying them. Here's a hint: Most people aren't casting off PCs in favor of a touch screen quite yet. After all, if the recent emergence of wireless Bluetooth keyboards for iPads and Microsoft’s own keyboard touting Surface tablet are any indication, there’s still a need for laptop style features - at least whenever work takes precedence over playing "Angry Birds" or flipping through family photos.

Thinking about getting a new device? Here are some things to think about before you go with a tablet.

Keyboard Questions

If you’re answering emails, a tablet is clear and simple to use, but it does suffer from touch screen typos, and attachments can be troublesome. In fact, the iPad doesn’t allow you to attach files through an email. Typing aside, the tablet method of swipe and select is gloriously intuitive for Web browsing and creative, paint-based apps. Even so, sometimes a good, old keyboard wins out, especially if you have a lot of typing to do.

If you think a tablet can replace a keyboard and your word processor, it simply can’t. The Microsoft Surface features a super slim keyboard embedded in its cover, but lukewarm sales suggest it hasn’t beaten a laptop for pure, speedy tactile feedback. Reviews of Microsoft's Surface tablet mostly found that its keyboard made it more practical for work - but still not as practical as a laptop. The same argument is offered by older gamers who prefer traditional controls and feedback on games consoles as opposed to a touch screen. (Businesses are using tablets' unique features to their advantage though. Learn more in 9 Cool Ways Companies Are Using the iPad.)

Battery Life

The average life of a laptop battery is five hours, while a tablet can last for at least nine hours. You can’t argue with those figures, but laptops are catching up. The MacBook Air 2013 models now boast between nine and 12 hours of use, and many other manufacturers are providing additional battery packs to extend use time beyond 13 hours.

Compatibility Woes

Compatibility can be a real problem in the tablet world, where so many competing operating systems are vying for space. There's iOS and Android. Microsoft tablets run Windows 8, the BlackBerry PlayBook tablet has its own OS (although it won't be updated any further). Mozilla has just launched a Firefox-based smartphone OS and is looking at tablets as well. The same goes for Ubuntu and other open-source contenders. The bottom line? No matter which tablet you choose, there's a lot of potential for compatibility issues.

Android apps won’t work on iPad and vice versa, although Google has made some Apple friendly apps like Google Maps, Gmail and Google’s cloud-based storage system, Google Drive.

Overall, however, industry leaders Apple and Android don’t play nice (and really, why should they?), and while file formats like Word are accepted by many third-party apps, trading documents and data is a traumatic process. You may get the guts of a file but the formatting will be wrong unless it is saved as a PDF, which you can’t edit.

In real terms, we’ve gone back to 1994 in terms of compatibility between competing operating systems, just as Google had almost solved the problem for laptops with a suite of free browser based programs in Google Drive that can read and convert almost every document and image format you’ve ever heard of. You can attempt that on a tablet, but there’s no "Save As," option or even a desktop for files - they all exist within their own apps.

Build and Design Evolution

Tablets come in a whole range of sizes; some are the size of a book, while others look as oversized as a flat-screen TV. But the arrival of tablets has forced laptops to adapt, and has blurred the lines a bit between the two. "Hybrid" machines like the Lenovo Yoga 11S offer a laptop with a touchscreen, which flips inside out to offer the best of both worlds, or at least attempts to.

By far, the better laptop solution for those on the fence is fhe ultrabooks, a term coined to describe ultra-slim and lightweight laptops. They are slightly heavier than tablets but bridge the previous weight gap considerably. If you think laptops are bulky and heavy, take a look at the latest high-end models from Asus, Acer and HP. Some have managed to lose a staggering 60 percent of their weight, thanks to high-powered processor technology and the removal of CD and DVD drives. (For more insight, check out Utrabooks: Hardware Pop Start or Has Been?)

Time for a Tablet?

A survey released by Intel in August 2013 found that 97 percent of the 4,000 adults surveyed said that a PC was their primary computing device and that they spend more than half of their weekly computing time in front of one. Of course, many people already have a home PC for work but need a tablet for their family and leisure time, as the living room continues to become a multi-screen environment. And while there's all sorts of debate about whether the PC will live on, if you have to choose just one, the old PC carries one more very predictable - and tangible - consumer benefit: You can get one that'll do everything you need for less than $200.