Well, I like that the print form of the letters and the cursive form are essentially the same, so the child doesn't need to relearn the form of every letter when he gets to cursive, but only needs to learn the joins; it's a very smooth transition from print to cursive (books A and B are print, book C accomplishes the transition to cursive, and books D through G are all cursive).
Also I like the "look" of it--it's very plain and streamlined--without all those fussy curlicues I remember sweating over with Maclean's muscular method or whatever that was all those many years ago (and which I subsequently dropped from my handwriting as soon as nobody cared what it looked like). Harpo wants to get things down as painlessly as possible, but he likes it to look nice, and the italic hand is rather elegant, which he enjoys. Groucho, who is in general still quite easily frustrated with this kind of task, has just dabbled in the first book but finds it quite satisfying so far--I like that we've found something he's willing to give a bit of a go without giving in to the frustration. I still function as scribe a fair bit of the time, but this series does seem to be helping them with their "writer's block."
I know a lot of people who use Handwriting Without Tears, and seem to like that quite a lot, too, so that may be another programme to check out.
peace
minnie