Just because Apple has released the new iPad mini and iPad 4 doesn't mean you have to race off and get it. Crazy, I know, particularly coming from the greatest iPad enthusiast site in the world, but that just goes to show you how true it is. When the time comes for you to get your next tablet, whether it's today or next year, and iPad or something else, you should look at what's on the market and decide what best suits your needs.
If you've never owned a tablet before, get an iPad. Unless you hate Apple, or specifically need a tablet that offers something Apple's iPad doesn't, it's the best damn tablet on the market and will provide the best experience for the most people most of the time.
But seriously, get an iPad.
If you have an iPod touch, the iPad mini will actually be less portable and likely have a lower screen density. But with equal specs to the iPod touch 5, a 4:3 aspect ratio screen, and ability to run iPad apps in addition to your existing iPod touch app, it could make for a compelling upgrade. If you don't need something you can slip into a pants pocket, the iPad mini can let you do more at an only slightly higher price. It also has a cellular option.
The iPad 4 is something totally different. Much bigger in size and display, and much more powerful, it's a good choice if the iPod touch is just too small, or you want something that can let you use iPad software at full size, for a full-on productivity boost. It's not an ultra-light laptop like the MacBook Air, but if you don't even need that much computer, it's a great choice.
The original 2010 iPad is getting a little long in the tooth. Underpowered, with not enough RAM, and not able to run iOS 6, unless you really want to ride it into the ground, both the iPad mini and the iPad 4 are compelling upgrades.
The iPad mini will give you much better performance while also also being far more portable. If the original iPad is too big and heavy for you, and you don't need the screen size but still want all your apps and content, the iPad mini is a great choice.
The iPad 4 will give you a much better screen and much, much more power. If the original iPad was the perfect size for you, but you want something that can run iOS 6 and all the latest software, and don't want to get caught in the same end-of-line situation with the iPad 2 next time around, the iPad 4 is your go-to.
The iPad 2 is still a good iPad -- Apple is still selling it, after all. So if you have an iPad 2, and you're still happy with it and it does everything you need it to do, you don't have to worry about upgrading at all. Still tight, enjoy, and see what Apple does with the iPad line in 2013.
The iPad mini isn't any more powerful but is lighter and more portable. The iPad mini has essentially the same specs as the iPad 2 but is only 80% the size and less than 50% the weight. If you're less about using the iPad in your lap, and more about trying to use it to read in bed, the iPad mini could be a better choice.
The iPad 4 will give you not only a Retina display, but an A6X chipset capable of properly driving it, and international LTE for even faster networking. If you held off from getting the iPad 3 because it wasn't the performance improvement you were hoping for, or because it didn't offer LTE in your area, the iPad 4 fixes both of those problems. It's the upgrade you were waiting for.
The iPad 3 was released only 7 months ago, which means there's almost no reason for anyone who got one to even consider upgrading to an iPad 4 or cross-grading to an iPad mini.
The iPad mini os slower than the iPad 3 and lacks a Retina display. You should only considered switching if you absolutely need something lighter and smaller and are willing to sacrifice everything else to get it.
The iPad 4, which adds new LTE and A6X chipsets, should on be considered if you couldn't get LTE with the old model and need it, or the performance really bothers you and you have money to burn to fix it.
If you've tried other tablets and not enjoyed them, or been frustrated by the lack of content in your region, or your ability to get help and support with it, the iPad is worth checking out.
So yeah, get an iPad.