It's really fast, has minimal boiler plate and supports functional programming without any of the "orthodoxy" of Haskell. That is, you can write a recursive function but also write a for loop.

Imagine something that can compete with C and C++, but doesn't require all of the low-level reinvention and memory management. It's like a high-level language for smart people that doesn't feel entirely impractical. It has some things that people bitch about (like having to use +. to add two floats and + to add two ints), which don't really bother me that much.

If it were more popular and had better libraries/platform support (unless that's changed drastically in the past year or so), it would be a serious contender for general development. Being completely honest, I think Jane Street is probably the biggest organization pulling OCaml, and from a navel-gazing standpoint you can either view that as good or bad.

Use it because you learned it and thought it didn't suck, I guess?

EDIT: changed some phrasing