Reactions to tablets are mixed. Some owners and bystanders alike are left scratching their heads, asking, "What is this good for?" For some people, the cost is trivial enough that the redundancy alone is worthwhile: an extra browsing screen, an extra music player, a movie screen in a pinch, and an extra-large Angry Birds machine. Most of us, though, don't want to drop even $200-300 for a budget model, much less $400-800 for an iPad or Transformer, if we're only going to use it for five minutes once a week.
My test, and the one disgruntled tablet owners seem to have failed to apply, is this: is there one task for which this will be my primary and preferred device? In other words, know why before you buy.
Many satisfied tablet owners, like myself, wanted a not-quite-so-dedicated e-reader, or more specifically a reader for highly visual media like magazines and comics. Others saw a space in their daily routine where they'd want to watch movies out of reach of their televisions or PCs. For others, just having something bigger than a phone and smaller than a laptop to curl up with while watching TV was enough. Yes, a lot of the tablet's value rests in being a general-purpose computer, but we also had in mind a single purpose that it would serve better than any other device in our stable.
If your current arrangement works just fine--if you always need a laptop handy anyway, or must have e-ink for novels and don't read magazines, or WiFi wouldn't cut it for your mobile browsing and you don't want another bill--then don't get a tablet.