Functional programming?

I've always avoided functional programming because of the following:

-It's pretty slow, FP by it's nature is slower than imperative because machine code is imperative and FP is implemented as an abstraction on top of machine code.  An optimized imperative C program(with splashes of assembly if needed) will always be significantly faster than anything else.

-Pure FP is very limiting.  It doesn't handle algorithm implementation, input/output, or complex data structures very well

-I don't understand the usefulness of meta-programming.  Lispers say it's bad practice to use macros when they aren't needed.  Normal programming styles never need macros at all, what gives?  From what i've heard it usually leads to convoluted programming flows, slow programs, and difficult to debug code.

-Languages designed for FP don't seem designed for real-world use. LISP doesn't even have normal math syntax.  Standard libraries are usually poor or non-existent.  Development tool-chains usually suck. 

Languages not designed for FP like Java require tons of boilerplate to program in a FP style.


Anyway, those are my gripes.  Do your thing /prog/ , tell me why i'm wrong and FP is amazing.

It is a different paradigm, that alone makes it worth investigating