I've been using F# almost since it came out. Initially, I was using it to simulate performance of large government pension funds. Lately, I've been building an infrastructure to allow me to build simulations of adaptive social systems. In terms of coding style, I find myself combining object-oriented and functional styles in the same programs, the object-oriented for interfacing with .NET/WPF types, and the functional where it seems natural. There are several things I really like about F#. First, it allows me to fit a lot of computation into just a few lines of code: No pages of curly brackets and semicolons. Second, I don't feel straight-jacketed into a particular coding style; I can use what is appropriate in the circumstances. Third, it is relatively free of arcana like annotations. Fourth, you don't have to know everything to do anything. And fifth, the combination of Visual Studio and the F# interpreter rocks! I hope this is helpful.