At least it is my best friend - and I am sure that it can become yours too if you get to know Input Box better.
I use it almost all the time now to debug my expressions. It is much quicker to enter expressions in an input box than going in and out of Charts to do the same. So I use input box as a scratchpad and development workbench to more quickly get to the expression that will get me the right calculation.
It took me a few months to discover what I thought I should have known from the start when I started learning QlikView. I kept clicking in and out of chart properties adjusting my expressions and fiddling with them and started hating all this clicking back and forth. I was told to use Text Box to put my expressions there to test them and I did that too.
Then one day I realized that Input Box can accept expressions too... on the fly. And of course that is much much quicker than going into Chart Properties and editing expressions. And it is also quicker and more immediate than editing Text Boxes too.
I soon learned to just create a List Box with some standard variables which I kept short to make it quick and easy. I usually have this kind of List Box with variables A1, A2 .... A9 or v1 ... v9 in all QlikView applications I develop. Then I can use that to test some ad-hoc expressions and interrogate the data model too from this scratch-pad with just generic variable names.
I can also explore any function more thoroughly but best of all I can break a complex expression into several more manageable steps by putting it into several variables referencing each other. It reminds me quite a bit about how I would work in Excel with complex formulas and it works very well. It mimics a column of Excel cells with formulas in fact. So now Input Box is totally indispensable for me. Speeding up my development and saving me a lot of frustration.
I will make a more comprehensive blog about specific use cases demonstrating the benefits with screenshots quite soon. Maybe already this week-end.
Hope this inspires someone else to adopt what I think should be a part of the practice of most QlikView Designer/Developers/Analysts workbench and practice.
I am curious if anyone else is using Input Box in the same way - I haven't come across anyone yet in fact.