I finished in the hour before breakfast on Sunday morning, having spent a fair part of Saturday struggling with it. Not the hardest Sabre, but I got very little pleasure from it. The one bit of pleasure was the initial PDM in connection with the missing letters. I agree with Hagen that the rest was a very boring slog, especially making headway in the top half. Getting the theme involved searching long lists generated by pattern-matching programs for commonalities, and even then some guesswork was involved. Normally one would expect answers crossing unclued encrypted entries to help in decoding the theme, but as several long answers were jumbled I ended up getting the theme first to help sort out the jumbles. It would have been far fairer in my opinion had the clues to the jumbles given the entry, thus consistent with the other down entries.
The clues were largely very fair, but I disapprove of uncommon abbreviations being clued indirectly, as was the case in two clues. Because it's so commonly used in cryptic crosswords, I think 'gong' for 'OBE', for example, is fine; once a setter strays off that track I think it's bordering on unfair. Where does it stop? Is it OK to indicate C (college) by 'educational esatblishment'? I often smile when a setter finds an unusual abbreviation that they use and indicate precisely and naturally in a clue. Such discoveries provide a satisfying PDM. I did not get any satisfaction when I discovered his indirect indications.