I can't really speak from any experience as I've only just started programming in F# myself, I think for the most part it's not meant to replace the things you mention. The reason I looked into it initially was because of its applicability with mathematical calculations and parallelism. Because of the .Net angle though you can mix and match your projects on Windows systems. Here's a Stack Exchange question about what proficient F# programmers use it for: http://stackoverflow.com/questions/568827/what-areas-of-code...