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I have an iPad, iMac, iPhone, and MBP. I had the iMac for home, MBP for the road, and the iPhone, well, as a phone. I bought the iPad mainly because I am an Apple fan, and a technology junkie, and thought of it more as an accessory at first, but boy did that change fast. Most of the time, by MBP is on its stand, closed, and whenever I go out, I take my iPhone and iPad with me. Its an amazing, amazing product, and Im extremely glad I bought one.
 
I've had all iPhones up to the 4S and still use it, two old MacBooks and an iPad Mini. Also have a Nexus 4 and a Nexus 7.

I've had an Apple TV 2 for two years that I haven't been able to use yet because I don't have a TV.
 
MacBook Air
iPhone 5

I find myself using my MBA mostly for media...iTunes streaming to my Apple TV, downloading media files, and also when I need to type out a longer document and don't feel like tapping endlessly on my iPhone.

I would say that I use my iPhone for surfing the web and daily activities like that much more than I use my MBA these days.

I have considered getting an iPad because I think it would make for a great couch/bed surfer...but I just feel like it is a bit overkill having all three. And I can't justify selling the MBA because I need a machine with more storage and more versatility than the iPad offers. Also, I think it might get a little annoying having to switch between the iPad and the iPhone when I get text messages that aren't iOS Messenger messages (ex. I'm laying on the couch, holding the iPad surfing the web - phone dings, set down iPad, pick up iPhone, reply, set iPhone down, pick up iPad...repeat repeat repeat). First world problem, I know.

I may pick up a retina Mini sometime next year though once they hit the refurb store.
 
I have an iPhone5, iPad 3 (LTE), and the newest Mac Mini.

iPhone: Goes everywhere with me

iPad: I use this quite a bit for school work and general browsing, photo editing etc. I take it with my quite a bit, but not as much as I would if I had the Mini.

Mac: Get's used the least but still has it's purpose for more in depth school work. Also used it a lot when working on stuff for our wedding.

I have a perfectly good HP laptop that I rarely use, I bought the Mini because, like others have said, I wanted everything to integrate.

For what it's worth I also have an iPod Nano (watch) and my wife has an iPhone5 and iPad Mini.
 
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