There are a few books one would like to give six stars, and above all of them there is this ten star book. As everyting has been said about The Elements, I would review this particular edition rather than The Elements itself.
First of all, this is a one single volume (be aware of Dover's 10$ book, it is only one thrid of the whole). This is usefull, of course, but to me it adquires an extra relevance in this particular item. The Elements may be the best math book ever (including Newton's Principia), so I just didn't want a book, but a beautifull book. This is the only time I chose the hardcover edition, and I think I did right. The book is printed in high quality paper, and the typeface is also beautifull.
As someone has already said, when you are reading through a proposition, and you turn the page, you find the diagram repeated, so that you don't have to be continually back and forth. In this book, where every propositions includes a diagram, this is not a minor advantage.
The final pro is that it is not interspersed with Heath's notes. "Euclid Alone has looked on beauty bare", so you better take this edition rather than the Dover's one. The book can be followed from the first proposition til the very last one, so no coments should be interspersed. Any critical notes about the propositions should be either at the end of each of Euclid's books, or if they are very extense, as Heath's ones, in a separated volume. To understanding The Elements, this edition prefaces suffice (and I even think that some parts are unnecesary, sometimes becoming redundant).
Green Lion Press has done a good job in providing us this beautifull one-volume edition.