iPads got their lease on life because of the tiny screen sizes of the original iPhone line. Once iPhones got bigger, iPad sales growth flatlined, and for good reason. They're the worst of both worlds - too clumsy of an interface (I'd say even with this new trackpad bolted on) for real work, and not pocketable.
When I want to do something trivial and immediately, the phone with a big screen does it just fine. When I need to do real work, a tablet interface is a miserable experience, so I use a laptop with all the normal tools an engineer needs.
I picked up an iPad Mini 2 and used it for a good year, but once the plus-size iPhones came out it went into the drawer and never came out.