There are several possible answers to this. First is, if you need to ask, you probably don't need it. I believe that covers 90% of the cases where that big touchscreen is invoking the lust for gadgets (read toys) inside males of all ages, yours truly included. If you consider the prices for iPad and some Android tablets from manufacturers like Samsung, Acer and Motorola, you can easily conclude that a laptop is a far, far better investment and cheaper too.
It's not that simple, though. We all know that Apple has the market cornered with iPad. Some analysts go even as far as stating that while there's a market for iPads, the existence of a market for tablets is questionable. The numbers bear them out. However, to really know how a tablet can add to our lives, we need to see how tablet owners use their tablets.
A typical iPad user is also a typical Apple customer. That means several things:
1) They are not in it for productivity or really adding value to their lives
2) They just have to have anything with an Apple logo on it
3) They use their gadgets to appear as part of some sort of elite club
There are exceptions, however. I know several executives who use an iPad for emails and browsing. 'Sent from my iPad' is becoming an increasingly common PS to emails and social media posts. One does realize, though, that emails and internet are CONSUMPTION of media rather than CREATION. That is where the dividing line lies.
Tablets are great for consumption. Browse the web, read emails, check on status updates, read books, view videos, play games etc. For all the stuff that doesn't require too much input from users, tablets are unparalleled. Their touchscreens make navigation a joy, and generally their screens have very high quality (new iPad leads in this regard).
Trouble arises when you need to DO something. Write a report, prepare a presentation, manipulate a photo, edit a video, run queries on a database. You can ONLY do all this on a PC. That PC needs to run Windows, needs to have a robust chipset and dedicated graphics support. It also needs to have a physical keyboard and mouse. Without all these, good luck preparing even a single slide of a PowerPoint presentation.
As far as media consumption is concerned, Windows in general has fallen behind. Things are more seamless and direct on a phone or a tablet. Case in point: what do you do when you have to email a picture? On a PC, you open a web browser, load up your email service, click Compose, click Attach a File, click on Browse, navigate the folder in the window that appears, click on the picture, click Attach/Open, then add email address in the address field, and click Send. On an Android phone or tablet, you open picture gallery, tap on it, click on the 'share' icon that appears on top, select 'Gmail' or 'Email' from the drop down list and click. You only have to add email address and click send. However, Windows 8 UI might change all that.
That said, for browsing and videos etc, laptops are generally as good as tablets if not better.
You cannot carry a tablet around in your pocket. You have to carry it in a separate pouch or case. So, if you do have to carry something extra, why not carry a laptop? It is quite clear that if you have a laptop and a good smartphone, there's really no need for a tablet in your life. However, if you choose to purchase a dirt-cheap phone for calls and texts, you can easily afford a tablet which will offer a much better experience at the expense of portability. Really, think about it: there is no real need for calls and texting to be integrated on a single device with email, Skype etc.
So we have found an answer. Or rather, a bunch of them
1) If you have a PC and a good smartphone, you don't need a tablet
2) If you have neither, buying a laptop is a better idea
3) If you have a personal laptop, you don't really need a tablet
4) If you don't care about productivity and have too much money, you're not reading this blog so go away :-)