It depends which Konis you go for - Im assuming Koni yellow sport struts
it will feel a little firmer as the damping will be different, if they are adjustable you can have it on the lowest setting which would give the least damping for your normal road use.
Your springs provide the push back against the force of bumps etc on the road but the struts provide the controlled resistance to that movement - in this case by oil flow through holes. The Koni holes are smaller so even though you still have the standard springs the resistance to those springs has increased.
I have used them before and they were a great product but I hardly ever used the full setting as much as the feel was fantastic I felt I was killing the car as every bit of road repair had an accompanying clang and shook the car.
If you are looking for the same softness as the OE struts - even wrx ones, you may be disappointed, if you don't mind it being a bit firmer you will be rewarded with increased feel and positive response in the drive. ;)
final word of warning though... its a slippery slope, I started with the shocks then found the anti roll bars could do with being a little beefier and then found that was putting the strain on the strut mounts so had top and bottom front and rear braces - then found I didn't need to run any camber on the wheels as they stayed upright around corners but the tyres were strained so hankooks were changed for yoko's - great end result but the bank account took a bit of a beating :D