Or perhaps I should say REB uniqueness.
One of the major reasons for using multiple Bible versions when studying the Bible in English (or any other language other than the originals) is to make yourself aware of alternate translations for particular passages. This goes beyond different ways of expressing the thought in English, to places in which the source language could be interpreted multiple ways, but even in the most literal translation, one must choose one or another option.
In Genesis 12:3, most translations use “in you will all nations of the earth be blessed” or something very similar. It is possible, however, to translate as the REB does:
All the peoples on earth
will wish to be blessed as you are blessed.
Now it happens I prefer the option presented in most other versions, but most people would not be aware of the alternate possibility unless they check a footnote, or use the REB. This is a positive value for a version which is known for accepted readings that are a bit out of the mainstream. (Note that I love the REB for my own reading; I will disagree with any translation on various renderings, and I don’t let that concern me. As long as a reading is well supported technically, I would never count it against the translation.)
The second one is in Psalm 121. Verses 1 & 2 are normally translated in a slightly ambiguous way. Is one looking to the hills for help? Is one rejecting the hills in favor of the Lord? This becomes more interesting when one seeks a Sitz im Leben for the passage. For example, if it is a processional song going toward the temple mount, looking to the hills could stand in for looking to the Lord.
The REB, on the other hand, renders unambiguously (or less ambigously, if that is possible!):
If I lift up my eyes to the hills,
where shall I find help?
My help comes from the LORD,
maker of heaven and earth.
In this case, I like the REB rendering slightly better. But my preference is not the point here. I think the REB can be a valuable addition to the library of the serious Bible student who does not know the source languages simply because it showcases some unusual readings. Of course, one hopes the student will be directed to the footnotes in all versions, as they often provide the same service.