If you are looking for an English translation you have few choices to be honest. I use both Brenton and NETS. NETS has extensive notes covering what it is, how it translated the Greek, what other translations are an on what they were based and so on. The introduction makes the following remark at one point :
Writing specifically on the topic of Bible translations, Nida and Taber3 envisaged no fewer than three such audiences.
It is usually necessary to have three types of Scriptures: (1) a translation which will reflect the traditional usage and be used in the churches, largely for liturgical purposes (this may be called an “ecclesiastical translation”), (2) a translation in the present-day literary language, so as to communicate to the well-educated constituency, and (3) a translation in the “common” or “popular” language, which is known to and used by the common people, and which is at the same time acceptable as a standard for published materials.
NETS is aimed primarily at the reading public identified in Nida and Taber’s second grouping, namely, a biblically well-educated audience, on the assumption that it is most probably this audience that has a more than passing interest in traditions of biblical literature other than their own. Since NETS has been based, however, on the New Revised Standard Version (1989), its character can be said to derive, in part at least, from the NRSV.
If they've achieved their goal here then I don't know if it would rise the your academic level or not. The other things to note picking some eyes out of the introduction, are the remarks about being based on NRSV, and the interlinear paradigm. I haven't used NETS enough to evaluate the impact of either of these but the introduction makes clear that the translation takes cognizance of the Hebrew original, using the NRSV as a base English translation and then using the Old Greek text to modify that base. That's probably an over simplification in my rendering of Petersma's remarks. In his own words then:
NETS has been based on the interlinear paradigm for essentially three reasons. First, the concept of interlinearity has superior explanatory power for the “translationese” character of Septuagint Greek, with its strict, often rigid, quantitative equivalence to the Hebrew. As Conybeare and Stock6 (and others) noted nearly a century ago, Septuagintal Greek is at times “hardly Greek at all, but rather Hebrew in disguise,” especially in its syntax and word order. Secondly, interlinearity not only legitimates the use of the Hebrew parent as arbiter of established meanings in the target language but as well absolves the reader of positing new meanings derived solely from translation equivalency. Differently put, the interlinear paradigm recognizes that unintelligibility of the Greek text qua text is one of its inherent characteristics. Thirdly, and perhaps paradoxically, the interlinear paradigm safeguards the Greekness of the Septuagint by emphasizing that its linguistic strangeness, rather than reflecting a form of the living language at odds with its Hellenistic environment, was made to serve a specific (possibly pedagogical) purpose.
and then later :
Once the aim and focus of NETS had been decided upon, a methodological directive seemed compelling. If NETS was to render into English the Greek half of a Hebrew-Greek interlinear diglot posited as paradigm, its English text might then be made “interlinear to” a modern English translation of the current Hebrew text. Put another way, since NETS was to echo the original dependent relationship of the Greek upon the Hebrew, one could seemingly do no better than to base NETS on an existing English translation of the Hebrew and to modify that base as dictated by the Greek.
and then :
In the light of what has been argued, it is thus appropriate to think of NETS along the lines of the Göttingen Septuagint: as the Göttingen editors attempt to establish the original form of the Greek text and in so doing draw on the Hebrew for text-critical leverage, so NETS has availed itself of what leverage the Hebrew can provide in arbitrating between competing meanings of the Greek. Moreover, just as the form of the original text differed from its later textual descendants, so what the original translator thought his text to mean differed from what later interpreters thought the text to mean.
Apart from the general introduction there are introductory notes for each book. All these notes are in the accompanying NETS Notes module.
I've not really studied it from the stance of whether I consider it a 'good' translation. It has certainly been helpful to have as an alternative to Brenton, rendered as it is in more modern language. Your question states "a good translation of the LXX, the Ancient Greek text", and in fact it doesn't describe itself as that but rather as a translation from Hebrew (via NRSV dependence) retrofitted as it were to conform to the Greek as it were. I actually don't know how much this affects what we see in the translation. I haven't read enough of it. The reader notes do enter into some justification for taking this approach, largely based on the acceptance of the LXX as a translation of a Hebrew (or Aramaic) original, on which it must therefore have some dependence. This is fine as far as it goes but we don't know the vorlage for the LXX so we don't know where such a text is at odds with the Hebrew text underlying the NRSV.
They further discuss the use of the NRSV as the base English text. This is justified due to it's compatibility with the NETS goals and familiarity to readers, being fairly widely used. In particular the NRSV literalness was considered an advantage.
I could go on summarizing from the reader notes but the essay deserves full reading in its own right. Hopefully the above in some measure though addresses the thrust of your question, and is of some help.