Have never ran 98ME, I have 98FE and recently built a new PC and put XP on it. So far I love it. 98ME is same kernel as SE, FE and 95. XP uses the NT, 2000 kernel. Is it worth it? For me yes. If you read the forums here, many people are more than pleased with 98 and ME. Others wouldn't leave 2000. Still others are like me and love XP.
I may not be much, but I'm all I think about.