I prefer translating into "Mother of God" when the Greek text uses variations on "Ματηρ Θεου" and Theotokos when the Greek text actually says "Θεοτοκος." It provides a linguistic continuity, a slightly more accurate translation and is just more poetic, in my opinion. But, that's just an opinion.
As far as the Jordanville is concerned, I really enjoy it. I'm a big supporter of Liturgical English, which sounds quite similar to King James English. It is usually fairly theologically accurate, as well as conveys the beauty of the Liturgy. The Jordanville can be somewhat clunky for those not used to older English and seems to, at times, stick closer to the syntax of the original language that what is comfortable for the average English-speaker.
In short: It could take some warming-up to, but I've found it to be an accurate, beautiful and edifying translation.