I've never seen it. Should I watch it?

definitely yes.

I dunno. It has nice scenery and some nastiness. I suppose it's kind of a horror film.

It is well worth it. 

I saw it for the first time fairly recently, going in with the concrete knowledge that banjos feature, and not a whole lot more. 

The scenes the movie is more well known for (sans banjo) were a shock and I didn't expect the level of tension throughout. 

I honestly thought there would be mosquitos.