Dear Reei,
I have not specifically used the "packaged" Music for Little Mozarts.
http://www.allegromusiconline.com/Merchant2/merchant.mv?Screen=CTGY&Store_Code=AMO&Category_Code=AMLMHowever, I HAVE tried the Lesson Book, Discovery Book, Workbook and CDs for Level 1 &2. I used it for my 3 year old daughter.
Lesson Book: overall good layout for a good story line to engage young children in the learning of music theory and note-reading
Discovery Book: I like the creative songs to solidify certain music theory concepts. Certain theme songs in here are also very catchy and good to review at each session.
Workbook: only good if you're doing one on one. If you have a classroom of children, this is rather boring and hard to control as far as time it takes to finish the activity page.
CD: contains a) all of the lesson book materials narrated then demonstrated and b) all the songs in the Discovery book played by an orchestra or instrumental group.
All in all, I think it's a good program for even a 3 year old though it says in the cover that it's meant for 4 and 5 year olds. I only bought the Lesson book and Discovery book for the next levels as I think I can do without the Workbook and CD. If you can play the piano yourself, there's really no need for the CD.
I hope this helps. Feel free to ask any further questions.
If you're going for note-reading proficiency, then I would recommend "We Hear and Play" by Taneda. My daughter liked it alot better for note-reading skill-building.
Sincerely, Violin