To put it bluntly, the LotR Unabridged version is not what you might think it is.
It is, very simply, an older gentleman reading the books in their entirety. No drama. No sound effects. No "multiple voices." Just imagine your grandfather reading you the LotR when you were little. It's about like that (don't get me started on the singing).
If you don't have the time to read the books to yourself and want to listen to it on the drive to work, that's fine. But be forewarned; this version (at least hte one I assume it is - mine was on audiotapes) is MANY HOURS long and VERY droll.
It has its place (I listen to it from time to time) but it is every bit as dry and drab as the book is. Basically, you could do just as well if you sat down with a mike and spent a week reading the book aloud. Hope that made sense.
--The Sigil