I actually liked Lost Planet, go fig.
But then, when I was a kid, I played ET on my friend's Atari 2600 and thought it was awesome at the time. Of course, back then, few of us were picky enough to realize it was the crappiest game of all time (according to many lists).
Worst game I ever played, in my opinion? Hmm... sort of has the problem of "Best In What Way" on the opposite extreme. I played a lot of awful MMORPGs - I hated Asheron's Call - but they had their good points too. I've played simple Ascii QBASIC demonstration games, but they weren't really intended to be comprehensive awesome games, is it fair to call them worst?