Actually, the ESV is a revision of The New Revised Standard Version. In other words they didn’t start from square one. The term “essentially literal” is a made up word by the publisher Crossways. Having said that it is a good translation for English speaking people that want a reliable translation for study. You can certainly do worse!
I thought it was a revision of the original RSV. The RSV is a good translation. The NRSV is not in my opinion - it takes too many liberties with the text.