When I use it, it always feels like you are forcing OO on something that would rather stay functional. I would agree it seems artifical, but then maybe its just familiarity.

In my experience, JavaScript has tremendously powerful capabilities both in terms of OO and in terms of FP, and if you can get comfortable with it, you can mix the idioms seamlessly. Using something like the Prototype library helps -- it adds power for metaprogramming as well as for more practical things like DOM and event manipulation.

Once you figure out OO idioms you like using, the main limitations are random annoyances like the lack of a clean idiom for linked lists and the fact that the JS spec doesn't require tail call optimization, so some functional idioms are going to be dog-slow.

I use Scala a bit - and it is OO/functional hybrid - it really steers you in the functional direction. I personally find it hard to reconcile OO with functional though (as in side effect free functional). I guess my personal (probably incorrect) experience with OO is all about mutability and state machines, whereas that is totally at odds with the rest of scala. So I end up not knowing what to do with the OO bit. I do like OO though, but I just can't seem to get it to fit together in my mind.