I think death gives life meaning. For me, life without death and pain seems absurd. Therefore the idea of eternal life seems ridiculous to me.
If I were to live forever, life would become devoid of challenge because I know I would be able to master whatever I wanted to, because I'd have all the time in the world to do it...So where's the challenge in that???? Without challenge, life would be boring. Without the lows in life, the highs in life would cease to have meaning. Without the fear of failure hanging over your head there would be no joy at success.
I think I would become the ultimate procrastinator in paradise. Instead saying things like "I'll do that tommorrow", I'd be saying things like "I'll do that next millenium", knowing I have an infinite amout of time to do whatever I might like to do, and It would be impossible for me to fail at it. This would make life BoRinG and pointless!