You know something is deeply right about a performance when it alerts you to musical subtleties in paragraph after paragraph, or when a familiar passage sets the hairs on the back of the neck bristling. What a dark, tortuous piece the Unfinished is - and how brilliantly Schubert re-works the old, over-used classical forms!
If all this suggests that the revelations are largely intellectual, then listen to the first movement of No 3. There's an ominous note in the Adagio introduction, as if the shadow of Mozart's Stone Guest had briefly fallen across the music; but then the clarinet slips free with its delicious, nose-thumbing fanfares and immediately the stage-coach is hurtling through sunlit landscapes. If the start of the Great C major is a little too plodding for my reconstructed tastes, the rest of the reading is as compelling as anyone could wish, with the astonishing, relentless finale driven - but not too hard. Add fine recordings, capturing the Lukaskirche acoustic to perfection, and you have a set that can hold its own in any company.