I haven't met a single person who regretted starting a quilting journal - any kind of journal. They all regret not starting one earlier and I am one of them. I started mine in 2000, about 14 years after I started quilting. I've been bad about including gift quilts, but I'm going to be better about that now.
My journal was a simple blank book with a ring binder (so it can expand with the photos). I also use a blog and keep photos on line. If a tornado hits the house, at least I have the photos to remember by. It has room for about 110 quilts or so (2 pages per quilt), so only about half full. I include a photo of the front and a closeup to show the quilting. I used to do a photo of the back, but I really want more documentation of my improved quilting skills. I try to include info about any new or improved technique as well as size of quilt, type of fabric and who got the quilt.