We are trying it again. We used it briefly a few years ago and did one full unit, but tweaked it. I found it lacking in many areas. We kept ds's work in a sort of main lesson book also, because despite the name I thought it had a LOT of pages/workbook type stuff. (I'm not necessarily against that, but ...) That enabled us to glue in his dictated stories, some of the pages we chose to do, and such and keep in it one place.It was not a program that had everything, or even a lot of, what I wanted.
We now have the 7-9 level and I like it better. Adding the literature units in has been a good addition, imo. We are just about done with the first concept. There is much that we have skipped, and lots that we enjoyed. I don't find it particularly creative so we jazz it up a bit- but I would do that with anything.
Ds is not a huge fan of writing so I modify that and sometimes do dictation to keep the focus on creativity and the expression of his ideas. I have also discovered lapbooking so we are creating a simple lapbook for each concept. This keeps the writing varied. The books are easy for ds but I didn't want to go up to the next level because I thought the subject matter and writing in this level was better suited to where he's at developmentally. We also use more Waldorf-inspired materials and use MBTP in conjunction of lots of other things.
We buy it used, and sell it when we're done- its very expensive!