This is more about economics than repairability. If you're out on a tour, certainly it's worth fixing so you can continue, and it can be done if you have decent skills.

However if you're at home, it's only worth fixing if you do your own work, and want to salvage a "B" wheel. If you have to pay someone $30 or more, then it's probably not worth saving.

If you do chose to save it, you'll want to use some filler, such as JB Weld to help the brake shoes past the open seam at the joint. If the rim sees hard braking the temperature changes may make your filler come out on a regular basis. The other alternative is to file shallow "ramps" at the open seam so the brake shoe can ski over it without catching an edge.

Overall, it will be decently stable because the tire itself acts as a splint across the gap. I've seen far worse last thousands of miles, but still wouldn' take it on a multi-day tour because of Murphy's Law.