In the day job, i use .Net(C#) within an all-MS environment. For my own business, I write in open source toolsets and frameworks(usually python stuff). So I can

In the day job, i use .Net(C#) within an all-MS environment. For my own business, I write in open source toolsets and frameworks(usually python stuff). So I can relate. The thing is, the .Net framework is not bad. I mean, aside from it being proprietary, the design is not that bad. Read up on what miguel has to say about that, I tend to agree with him on this topic. If only they would embrace their community... What's wrong with the .Net framework is the same thing that's wrong with using Windows as your platform of choice for development. If you don't hit any problems, then you will be very happy. But when you do hit problems(and you will) then you'll realize what the problem is with closed systems. So in short, closed system even if you can read the source code, its very difficult to do anything with it. Inadequate documentation that are often wrong with edge cases. Lock in to specific technology and often specific versions. Not enough interaction with the community of developers in terms of bug reporting, change description and the like.