Yes, iceplant is bad for a number of reasons! 

First of all, it is invasive into grassland and meadows.  It releases salt into the soil, raising the salt level high enough to inhibit other plant seeds, especially grasses.  It also doesn't serve as a food source for animals.  It can out compete the native plants for water, light and space.

Secondly, it is really bad for erosion control!  The plants are very heavy with very limited and weak root systems.  As they become heavier, the sheer gravity can cause the hill to start sliding- taking with it what little top soil already existed on the slope!

It is also not a good plant for fires!  The soft succulent new growth does have a high water content so it doesn't burn, but the dead leaves take a very long time to decompose so there is a higher amount of dry and dead material under the plant than a typical plant.

If you would like to know more about iceplant and what alternative plants are out there, please click on the underlined links for more information:

http://www.plantright.org/plants/invasive.php?invPlantID=18®ion=none

http://wric.ucdavis.edu/

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74139.html

http://www.cal-ipc.org/

http://www.laspilitas.com/garden/howto/slope.html

Please don't plant a weed!