If there's anything I dislike more than jumbles, it's letter counting (NB, Harribobs!). But in this case the jumbles were ameliorated to a large extent by the theme words. I wish I could remember what tipped me to the theme - sometimes these things just happen - but it was an enormous help with filling the grid.
For me the alphanumeric tomfoolery was a final confirmation stage - not entirely necessary but I did it just so I could collect my gold star from teacher. I can see that reliance on this to get the theme could be a nightmare - you'd have to cold solve enough of the clues to identify the relevant clues - and no doubt that's why opinion is divided. I still found this bloody hard, but I'm definitely in the positive camp,