At work, tablets proved to be a popular gift. And though I find tablets can be useful, they are not for me. My needs are not meet by tablets at all, I prefer ultrabooks and smartphone combination.
The main reason for this, is that I prefer the ultrabook when I'm not moving around. Since I tend to read, while I've several other thing running on the background like my audio player and IMs, or writing, the tablet doesn't really does a good job at that.
When I'm on the move, I like to have something I can get on my pocket and get out of the way when I'm not responding to messages, checking for directions, taking a picture, or listening to music.
As such, the tablet doesn't really fits my needs. When I write comments, and specially on my blog, I prefer the comfort that a physical keyboard gives me. Call me old fashioned, but I like the feedback I get from the keyboard with each stroke. And for the short messages on Whatsapp, Facebook, or Twitter, the smartphone does the job quite nicely.
I agree that tablets are quite useful, at the right place and time. As with ultrabooks and smartphones, they are tools that serve a purpose. Yet, none of these tools are the answer to everyone, since we all have different needs to fulfill. As such, we need to keep in mind that those needs determine which tool will be the best for each of us.
I don't see any tablets completely replace laptops or PCs. At the end, all will have their places.