I don't read that many plays, but I should probably read more considering that I work in theatre. I picked this one up primarily because it's famous for coining the term "robot". The creatures in Čapek's work aren't really what we typically consider robots today, though--they're more biological than mechanical.
Written in 1920 and first performed in 1921, this was way ahead of its time. The machines-rebelling-against-their-masters trope is ubiquitous in contemporary science fiction, and R.U.R.
is arguably where it all started. It's a dark and apocalyptic vision of the future, but it's also a social commentary and witty satire. There are quite a few bits that are very funny. I wanted to read this for the historical contribution it has made, but it truly stands up today and I enjoyed it based on its own merit.
I'd love to be involved in a production of this.