I miss Visual Studio, yes, the IDE
There's an old saying: "You don't know what you have until it's gone.".
No, I don't talk about this, but I am talking about Visual Studio.
For more than half a year now I've been doing more coding in MATLAB and in Mathematica compared to coding in Visual Studio (and C#). In terms of library/built in functions, nothing can beat the comprehensiveness of MATLAB for doing scientific/engineering computing. It has them all, numerical computation, linear algebra, etc up to toolboxes for Fuzzy Logic, Neural Network, Signal Processing, etc. No C# library is (or will ever) close to this. In terms of language, even if with Lambda Expression, there is no way C#/.NET can be compared with Mathematica to do Algebraic Computing or even its higher order functional style.
Yeah, it is not fair to compare the C# (.NET) with MATLAB and Mathematica as C# (.NET) is a general purpose language/library, while MATLAB & Mathematica were by design made to do scientific/engineering/mathematics computing.
But, in terms of IDE, I can say MATLAB sucks big time! 
The m-file editor of MATLAB (IDE) just so "old fashioned" compared to the sophisticated-sate-of-the-art IDE like Visual Studio. I've never used Wolfram Workbench to do Mathematica programming (I just use the standard editor within Mathematica IDE), but I feel Visual Studio is still a more superior IDE.
Not just the IDE, the MATLAB has another limitation that I hate. All functions there are global! There's no sense of packaging or namespace. If you've been doing Component Oriented and Object Oriented stuff you will look at MATLAB with strange look, "everything is global?". Well, they say the newer MATLAB has OO capability, but I haven't look into that.
But, again, what I really miss is the VS IDE. When coding in MATLAB or in Mathematica, I do miss things I took for granted in Visual Studio like Intellisense, Debugging Tool, and other IDE features. In VS, when I type a function name, the IDE will autocomplete the function name, will show the parameter list and the overloads as well as the description and the types of the arguments and the return value. In MATLAB, I feel like I'm blind. You have to memorize all these stuff.
Man, I do miss my Visual Studio IDE. .
O, I don't mean I don't code in C#/Visual Studio anymore. I still do. But when I code in MATLAB and Mathematica I wish they have as cool as VS Intellisense & Debugging capabilities. Now I appreciate VS IDE more! Intellisense does ease your life.