Schloss Blumenstein is a compact historic landmark that helps explain Solothurn beyond its main route. The appeal is partly the structure itself and partly the perspective it gives on the town’s older civic, military, or estate history.
Treat it as a deliberate short stop rather than a full-day attraction. Check opening details where interiors or towers are involved, and leave time for the surrounding walk, since the approach and views often carry as much of the experience as the building.