What Makes a Good Commentary?

A few different bloggers (see, e.g., Michael Bird's post at Euangelizomai) have mentioned something about Tremper Longman's recent paper on the writing of commentaries.  I didn't hear and haven't read the paper myself, but Bird's post outlines Longman's reasons for biblical scholars to continue the practice of producing commentaries even in the midst of a landscape seemingly saturated with them.  All that to say, this prodded me to ask what qualities make a good commentary good.  I doubt any of us could begin to answer this question in a purely theoretical manner, but, after engaging in exegetical study of different passages with the help of different commentaries, perhaps it's possible for us to extrapolate some rules of thumb.  Here are a few of mine in no particular order:

1) sensitivity to the Bible as literature, as a library of literary works employing literary devices that demand explanation and appreciation

2) recognition of the continuity between the two testaments, OT commentaries unpacking the forward-looking dimension of the OT and NT commentaries honoring the OT backdrop for the NT

3) commitment to the authority of Scripture, even when it challenges modern sensibilities

4) treatment of the grammatico-logical connections between words, phrases, clauses, sentences, paragraphs, and so on

5) specification and fair-minded consideration of interpretive options for difficult passages (both well-worn and newly proposed options)

6) respect for theological integration with a view to shaping the mind of the church

Any you would add?