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Python (programming language)

The least reliable platform for windows users. Scipy has problems. Numpy has problems. C extentions have problem. .Net support have problem. Server side stability? If you are not on linux but windows then that also has problems. 

If you are not a linux client and you are not gonna build your application with entirely python then don't get involved. The stuggle would eat you.

And frankly, although it has been decades from the first release, it feels like it's still an experimental tool. Maybe I'm too harsh on it.