Well, their arguments[1] are quite compelling in general, rest of the software[2][3] seems to be highly specialized and specific, I'm guessing there is a lot of maintenance that has to be done still.

- [1] http://www.symbolics-dks.com/Genera-why-1.htm

- [2] http://www.symbolics-dks.com/Macsyma-1.htm (general purpose symbolic-numerical-graphical mathematics software product)

- [3] http://www.symbolics-dks.com/PDease-1.htm (general purpose software that uses Finite Element Analysis to obtain numerical solutions to a large class of partial differential equations)