I own the Jazz II but I have not had a lot of sewing time on it. It was not difficult to set up and it is capable of many more options other than straight stitch. I recently read some quilters say that they got better results free motion quilting when they left the feed dogs up. I do not remember where I read it.
I like the fact that it is not computerized. I had some problems with tension when I first started using it, but I was reading the bobbin winding diagram incorrectly.