use imovie for about 2 years... very good, very intuitive, good results for homemovie, special effects possible with qt pro (e.g. pic-in-pic), re-import footage as .dv etc.pp.
no sound editing (sorry, functions are VERY limited, fading - that's it)
now, fce:
totally different concept. coming from the professional area, it's a "down-sized" version.
no, it isn't down-sized! that's pro stuff:
learning curve very high, you need to read the missing manual (;-)), it is not a quick "load your camcorder stuff on da computer, cut it into short pieces, add some umpf-umpf music - DONE".
BEFORE you start to work with fce, you need a concept for your project - otherwise you're lost!
BUT:
results are impressive! this IS a pro tool! e.g. titleing, moving pi-in-pic, post-production effects (coloring, matting etc).
imovie is a toy. fce is serious.