We will show by "generic smoothness" that the big quantum cohomology ring of isotropic Grassmannians IG(2,2n) is generically semisimple but the small quantum cohomology ring is not. That non-semisimplicity leads to a decomposition of the small quantum cohomology ring that relates to a certain decomposition of the derived category of IG(2,2n) in a so-called Lefschetz exceptional collection. This is based on joint work with A. Mellit, A. Kuznetsov, N. Perrin and M. Smirnov.