I have a Stubben that looks like that and I use it in my lesson program. The cracks are only through the top layer of the leather. It works just fine. As long as the seat and topside flap leather and stitching are in good shape, I would keep it. You won't find another quality saddle for that price.
Yes, it will need reflocking and the whole underside of the saddle replaced eventually, but it should ride fine for a long time. Just keep it cleaned and conditioned and it won't get any worse.
Wasn't there another saddle that was the same size tree wise but a more appropriate seat size for you? Do you have pictures of that one? Is the leather better?
Perhaps this is too forward of me to ask (or maybe you posted it and I missed it) - but what are you spending on this one? I ask because you can most certainly find a quality saddle for a good price especially in this economy. I got my kieffer for $500 (or was it $400? Idr) and it's in stellar shape. I wouldn't have paid that kind of money for something that wasn't great.