My impression of the Suzuki method is almost all positive - my two daughters started at nearly-four and nearly-five.
The younger one lasted three years with it and then moved on to the cello; the older lasted four years and then went on to "mainstream" lessons - actually I taught her myself for one term, entered her for grade 1 in which she got a distinction, and decided I'd stop there as I had a 100% distinction rate as a violin teacher! and then we moved so she started lessons in school and only stopped at grade 5. The reason I took her out of the method was that she was becoming apathetic towards it, and not really improving her playing. She was going through the motions of what she knew she had to do, and if it wasn't perfect, well, she was doing it, what more could we ask? So I adopted the mantra "Stop playing the violin and start playing the music" - basically, it had to sound right - if you can make the best possible sound by using your nose and your toes, then use your nose and your toes, but you will probably get better results with careful placing of the left hand and much more attention and sensitivity with your bow arm.
The little one struggled with the method in some ways because she was, at that age, physically clumsy, and frustrated, since as her teacher said, she was about the most musically responsive pupil she'd had, but at the end of a whole year she had only just mastered the Twinkle variations, and it was another two years to graduate from book 1.
I realised that everyone finds their own time and manner to come ut of the Suzuki Method, but that in no way suggests that it's a bad thing - inevitably, though, it is a step towards further and more advanced study.In our group, the largest outside of london, with 58 when we were there, there were players who got into the National children's Orchestra and stayed with the method until about grade 7.
What I certainly found was that if you compared a Suzuki violinist with a more traditionally taught child at the same age, certainly up to about 8, the Suzuki player had not only better posture, but MUCH nicer tone and far better intonation. This was because the method was entirely based on listening in the early years and they had not been held back by having to try to read as well. Our teacher, who had been trained in Japan twice for a season at a time, said that in Japan they didn't start reading until they could play the Vivaldi concerto in A minor. She started them a little earlier because they were bound to find in Britain that they would be making music with children who had been taught in mainstream "reading" methods so they would need to read. She said that in her experience, after all the listening and the tactile experience, the reading came "all of a piece".