there have been lots of flannel discussions---what are you looking for? did you have specific questions?
i can tell you some people (like me) love to work with flannels and use them alot- others hate to use flannel and talk (mean) about it
some people pre-wash their flannels 3 or more times before using it- some of us do not-
flannel just like other cottons come in a variety of qualities/weights/weaves
thin, single sided, inexpensive flannels will stretch, shrink quite a bit and pil when washed
good quality, heavy double sided flannels do not stretch much when working with them, do shrink but not much more than any other cotton quilting fabric, and get softer, loftier better with washings.
they are a looser weave than regular quilting cottons- so the edges (sometimes fray more than 'usual') i use heavy, double sided flannels and a wider seam allowance than the usual 1/4"
if you type flannel quilts into the search box you will find pages of discussions about flannels....and pages of quilt pictures of flannel quilts. if you have specific questions- just ask- you will receive hundreds of different answers