Since our liturgical readings are drawn from the NAB, I’m not sure why you wouldn’t want to use it.
Actually, although the texts were originally from the NAB, they had to be revised before they could be used in the Lectionary. This is for the Mass translation we have now–I don’t know if further revisions were made to the texts for the new Mass translation.
Plus, of course, you don’t have footnotes at Mass.
To the OP: I would certainly not go so far as to say you should never use it, but I find that it is a little bit too much like having someone chew your food for you. I would prefer a translation that is a translation, with a bit less interpretation, myself.
I believe you can find both it and the RSV-CE and the NAB online. Pick some passages from both the OT and the NT that you are familiar with, read both versions online, and see which one you feel more comfortable with. The right Bible, as they say, is the one you will read.
What I would strongly recommend against, however, is “The Catholic Study Bible” (Oxford University Press) which is based on the NAB. I got one when I first came back to the Church, and it almost sent me back to the Protestants, because the (somewhat Evangelical) Protestant Churches I had attended clearly believed in God and the possibility of prophesy (e.g. in OT times) and miracles and so forth. Reading the Catholic Study Bible, I was beginning to doubt if Catholics really did. In the end I actually threw it away (well, technically, ripped off the covers and recycled it), and I am not a person who gets rid of books often or lightly.
So, as long as you just get the actual Bible, and don’t pay too much attention to footnotes and so forth (which in any translation are not part of the actual inspired text anyway), the NAB is OK. But I’d check out other versions as well before deciding.
–Jen