I had my first tablet quite some time ago. It was not quite like the tablets we have today, it was a Nokia N800 which was a true Linux tablet with a 4"-ish screen that was used with a stylus. It looked like this:
I loved this little device, but I had some serious issues with that it had no keyboard as the touchscreen wasn't great and that it was a bit underpowered in terms of hardware to the point that the browser even slowed down the system on some websites. I did contemplate figuring out some way to use it with a USB keyboard through the micro-USB port, but that seemed to limit portability a bit too much.
I cut down on using it a lot once I got my first actually good smartphone (the iPhone 3GS) as that covered like 70%-80% of of what the N800 did, but what finally killed my usage of the N800 was that the battery in it essentially died and I didn't feel like buying a new one.
Right now it sits on my desk at the office, mostly as decoration as it is out of battery almost all of the time.
Even with having this I did not see how an iPad could fit into my computing. It was so much more limited than pure Linux, and I couldn't see why I would want what was essentially the size of a netbook but without a keyboard. I was instead eyeing some Asus EEE-machine, a purchase which I'm now glad I didn't make after seeing my wife's use of an Acer Aspire One which is significantly newer but still not good. In retrospect it's a bit silly that someone who develops multitouch software for a living had problems seeing the use of a multitouch tablet. It is not specifically that I didn't get the form factor, but my use of computers differs from that of most people.
In 2011 I got an iPad 2 from work, and I was quite psyched to play with some of the apps and games I had seen people post about on the internet. Even so I didn't think I would use it that much after the intital spike.
Boy was I wrong. After 1.5 years the iPad (iPad 2 to be exact) is my most used computer at home in terms of time used per day. I do have an office upstairs at home with what is probably the best computer I've ever used, the 15" retina MacBook Pro, in it connected to a nice mouse and a mechanical keyboard where I do development and some other things that are most efficient to do on an a "truck" computer, but is only like 10-20% of my computing in the home now.
For most things like reading app.net/twitter, reading news,answering quick e-mail, checking in on zendesk, playing games, blogging (like now) the iPad tends to be my go-to device. I actually got myself a Logitech ultrathin keyboard case fairly recently, and that really helps with some somewhat longer writing (like this post), but that only comes out very rarely.
Most of the time I just use the iPad on it's own, as-is and it is amazing how much I can get done on it. It's surprising how much of my needs are covered by Tweetbot, Netbot, Reeder, Safari, Prompt, Elements, Dropbox, 1Password, iTeleport, TeamViewer and a handful of other apps... plus of course a bunch of apps on my iPhone. I've even done coding in Textastic in some situations, mostly scripting, but even some C and then compiling remotely by running make in Prompt.
I can not think of any device that would better suit my needs, except for maybe the new new iPad (can we all just agree to call it the iPad 4?). I don't find my iPad sluggish or blurry, but I think I would enjoy retina and a faster CPU quite a bit.
The big change I see is that computing isn't such a sealed off thing and that it falls into my day more organically. Grabbing the iPad and reading news in the morning or sitting down on the couch and writing a quick e-mail while my son is watching a kid's show. It also makes computing more accessible as it doesn't involve me going and sitting in a corner away from everyone, but rather being accessible while quickly doing something.
That has actually made it far easier for me to be there, with other people, while still feeding my need to be connected with the outer world. This is how the iPad has changed my computing and my life in general.
It will be very interesting as more computing devices get popular to see what will be the next thing that will change my computing. I'm not yet sure what will fit my life and the way I do things, but I'm sure there are things out there I haven't even thought of yet.