First one has to get over the prejudice against diglots and other NT texts with aides. I was taught old school that you used an "unmarked" text and even a dictionary in the back was cheating. But the better my Greek becomes, the more convinced I am that reading an unmarked text is a waste of time because it does nothing to IMPROVE your greek. So your choice, if you want to do "arm chair Greek," (that is not having to have two books open at once) is a diglot or Zondervan's Reader's Greek New Testament which has all the rare words in footnotes. Both of these, I suppose, could be abused, but we are not talking interlinears here. I recommend a diglot AND the Reader's Greek NT (a revised edition is on its way.) The Reader's Greek NT will help you in vocabulary acquisition and a diglot is great because no matter how good your Greek is, it is a good idea to check your mental translation against the experts. I find that I still misconstrue a lot of the text and need to check my work.
As to this book, the font used here is a good one; Nestle Alland is probably the most pleasing on the eye, better than UBS 4 which tends towards italics, MUCH better than the horrible italicized font on Reader's Greek first edition. (Hopefully the revised edition will have a better font.) The size of this font is okay, a little smaller I think than UBS 3, but the size of this book is nice because it is big enough to read clearly and small enough to carry around. The NET diglot has a much larger font and I would consider this in making a decision. A large font makes reading the Greek NT MUCH more enjoyable, but the NET size is hard to carry around, so there is a trade off. It should be pointed out that in both books, much space is wasted on the page, better layout could produce a LARGER type with a SMALLER book.
The criticial aparatus used here is pretty awful. UBS is much more user friendly. NA is virtually impossible to decode, with the variants themselves abbreviated and without accents, and the symbols used mar the text a bit. The NET diglot uses the identical apparatus and text, and as far as I know UBS does not make a diglot, so again there are trade offs.
The translation used here, RSV, is a fine overall translation but a more literal one would have been much more helpful, e.g. NASB or even a literal "crib" written for just such a text. Often a literal or near literal translation is the best grammatical commentary on a text, and RSV is wanting in this again and again. This is not the place to critique this translation, but I would say that after comparing RSV to the Greek while reading this, one has to conclude that the RSV is far too free. Now, mitigating against this in this book is a wonderful feature where variant English readings from the KJV and the old ASV are given. These are very helpful in unpacking the Greek, which raises the question why one has to use centuries old translations to figure out the Greek. I think one will have MORE respect for KJV and ASV after using this text. However, the readings are limited, often a difficult Greek passage will only have a RSV reading which is really a paraphrase, helping you, I suppose, discover what the text MAY mean, but not what it SAYS. This text also has the very annoying element of often having the English variants on the next page instead of the facing page. Still, this feature is very nice to have.
So, overall I would recommend this diglot especially if you are on a limited budget and you want a smaller text. However, I think I would pay the extra money and get the NET diglot. (See my review of that work.) Actually, I would get them both.
The cover on this book, as on most UBS and NA stuff, is cheap and the binding here is known to fall apart. That is another reason to look into the NET diglot.