I think it's a really great method of learning an instrument Ships. It works on the same things we do unconsciously when we learn to talk. We repeat things over and over, memorise them and build on our vocabularly bit by bit. You do need a skilled teacher who totally knows the method and how to teach it. Until around book 4 there is no use of written music. Everything is done by imitation just as we learn to speak by copying what we hear.
The younger a child learns the better. Around 3 years old is ideal. The more compliant and placid a child is too, the better!!!! I took my ds to a suzuki violin group at 3 and she wasnt having any of it. She just disrupted the lessons so I had to take her out!LOL In the end she started 'normal' piano lessons aged 8 and did a lot better.
Suzuki method also needs the child's parent/carer etc to learn alongside them. You would sit in on lessons so you will know what the practice consists of. At first 5 mins a day practice (best to do short sessions) building up gradually to 10 etc etc. It can get 'results' very quickly and works on the assumption that any child who can learn to talk can learn an instrument. The child learns real 'tunes' immediately which is really rewarding and fun and the more fun and progress they make the more they should want to carry on learning. Anything that encourages a child to learn an instrument is wonderful I think. Even if they don't go on with it, just having the discipline and experience of learning an instrument and being exposed to 'classical music', for how ever long is something that is life enhancing and valuable.
Way way back in the 1970's (I'm 51), I was lucky enough to go to a Shinichi Suzuki and Yehudi Menuhin demonstration that the peripatetic violin teacher at my school arranged for all his pupils' to go to. I've got a dreadful memory but I havent forgotten the impact it made on me, not to mention the disbelief of hearing 3 and 4 year olds playing perfectly a piece that I'd struggled with for ages with was still making a total mess of!!!!!
Would totally recommend giving it a go.