If you are asking, I would say they are probably not going to impress you.
I find them fine for what I use my iMac for which is just a computer. I dont really watch movies on it nor do I listed to music expecting anything but computer sound quality. I have a 50" plasma and a couple of stereo setups for that stuff.
When I move my iMac down to my son, I would imagine that he will immediately wanted upgraded speakers as he uses his computer for music, movies, and such.