A review of Vergil's work could be so funny, but I'll pass on that and comment on R. D. W.
I think this is the best balance for a reader who does not wish to get into a profound study of the Aeneid, but to get through the Latin text first. With the patience of a good teacher Williams walks you through that task. The commentary divides the text into thematic morsels, with a synopsis and an introductory paragraph to provide some background. If your Latin is somewhat rusty and you can't at once feel the nuance, the synopsis is an immense help even if it contains slight spoilers for the next couple of dozens of lines.
Williams is very keen on making you appreciate poetry, and has two acts up his sleeve: first, he draws your attention to technicalities of Vergil's craft, and I think that his indications as to how rhythm is tied to the theme of the verses, as to what kind of alliteration is considered harsh, and how diction influences perception, contribute hugely to the appreciation of poetry – Latin poetry, because it explains what we coudn't skim unwittingly from a text that remote, and modern poetry as well, because Latin forces the procedure and the analytical tension you'll have to keep applying. Secondly, Williams is very fond of drawing parallels with (early) contemporary literature, exposing the impact The Aeneid (called by T. S. Eliot the one true classic of the European literature) had on everything that has been written since, so that you get a fair share of your favourite lines from Spenser, Milton, Wordsworth and others exposed as wonderful and precise variations on themes set by Vergil. Which Vergil himself would highly approve, as Williams shows by exposing his sources as well: Ennius, Catullus et al.
I am not sure to what extent Williams is indebted to Servius, because Virgil's study is steeped in his commentary, either gathering corroborating evidence, or—very much less frequently—gainsaying, but he does seem to have a fairly direct landline to the ancient classicist.
Cultural references and mythology are explained in fair detail without falling into a rabbit-hole of research with bibliographies as long as the reference is subtle. If you need that kind of study, consult Horsfall, who has thrice as much commentary text per line; I felt I was reading Horsfall, not Vergil—which is fine, but it wasn't my intention. Williams keeps decently transparent.
It has been pointed out by angry reviewers on Amazon that they couldn't read Latin, and Williams did not help. I do believe them! On the other hand, I couln't say why he chose to translate the phrases that he chose. They certainly weren't the most complicated by way of grammar or references. Whatever his criteria, I couldn't discern them—but I can't get angry at him for that.
What does have a great share in that one star that I took off my glaring rating is the physical edition. It is a rather bad reprint of a 1972 Macmillan edition (which is not only out of print, but virtually unretrievable) by Bristol Classical Press, and it will have you guessing the ends of lines on many pages and raving about the binding that you have to struggle with. I understand that Virgil doesn't sell well these days. Well, so there it goes.