It looks like a lot of pieces are already sewn to make up more blocks, so if at all possible, I would finish it. I wouldn't want holes, so I'd either re-do those areas, or applique over the holes, as someone else suggested. The quilt is really lovely, and I think you will cherish it once it is finished. As a ufo, how much are you really going to appreciate it? Also, if it remains in pieces, someone in the future may just trash it all, not knowing what it was or what it really meant to them. Once it is a finished item of some sort, you can attach a label to it so descendants will know what it is.