i've got a creative Zen Vision M, my sister has an ipod. the ipod has broken once and been replaced, been fine since, although it's only been three months yet. the Zen is generally good, but sometimes it will play tracks with crackly distortion, if i skip to the start of the track it plays fine but it shouldn't be happening. also, on random play if you turn it back on after a while it doesn't remember where it was and starts over again, the ipod will run through it's entire contents one song at a time even if it takes weeks!
i think all players have pros and cons, we hear a lot of horror stories about ipods, but that's possibly just because there are so many of them out there! my biggest objection to apple is their monopoly mindset, if you buy from itunes it will only play on an ipod. that's why i won't buy one.