I have blogged about this programme previously which you can find here and here.
I have been using this programme with one of my students who struggles with decoding and spelling who is currently reading at level 17/18.
I have noticed huge changes in Evan since using this programme daily. There are mini-lessons which use specific letters and a "special" word that they have to build up to spelling. The lessons start off by spelling small letters like "as". The teacher gives specific instructions to help them to build more complex words, eg; add a letter to the start of the word "at" to spell the word "pat". The student has to use their sound knowledge to word out where the letters have to go. Evan's confidence with spelling has grown so much that now he doesn't need as specific prompts, now we say to him "use three letters to spell the word cat". The managing self skills that Evan has gained has transferred to his writing. Previously he was unable to write a sentence without adult support, this week Evan wrote a story about his cow puppet independently.