I recently began this, and chose the four-volume set. It’s expensive and difficult to get started, but I definitely wanted the full experience, so to speak (even though it’s rare I have time to pray all the hours of one day). My experience of the liturgical calendar has definitely been enhanced, and I’m not sure this would have been the case with Christian Prayer. Also, I really like the Office of Readings so I don’t regret my choice. Still, Christian Prayer was made for laypeople/beginners, so I’m sure for many people it’s an easier and more spiritually profitable choice.
I also bought the St. Joseph’s Guide, only to find that I didn’t need to: the set I bought came, to my surprise, with both this (which is extremely helpful, almost essential for beginners like us I’d say. Although I’m almost certain I’ve encountered an error in it) and a bunch of other supplemental material which I’ve found very helpful.
The only downside, besides the difficult nature of LOTH itself and the expense of the set, is that this set was printed in the 1970s, and the covers and little images on some of the pages are rather ugly, 70’s-style monstrosities. Also the volume for Advent and Christmas has a rather feminine and dated turquoise-blue color to the edges of the pages. A few unpleasant hymns and a dirth of thees and thous in prayers I already knew also are a little annoying, but that’s to be expected in liturgical material from this era, and for the most part the hymns are surprisingly good. Some additions to the liturgical calendar for the United States are absent in the volumes (Bl. Kateri Tekakwitha, for example), but the supplemental material they included with it covers them. I don’t know if newer, more modern publications exist.
The whole thing ought to be retranslated eventually, but it looks as though that won’t be for several years.