they have good everyday driver dampening (highway/normal stoplight driving) but when it comes to handling they can't take the abuse. they are factory length struts so when you lower the car with whatever springs you use you lose the travel of the strut, this results in some wicked bump steer under hard cornering and when hitting large potholes you will hit your bump stops(or strut mounts in my case) for sure.
so just be pre warned that these are better than stock but not much.
I've had mine on my car for 3 years now with eibachs and I have no complaints about ride quality but my beef is with the handling.
my best advice is if you just want to lower the car than go with kybs because it will handle better than stock, be more stable etc etc but if you plan on running it hard i'd suggest something with a little more travel or shorter shock bodies(ie. konis or full coilovers).