I love it.
The most aggravating thing is just vibration between the plastic roof and the roll cage at certain RPMs, but I'll slip a little bit of padding in there and cure that.
The only times I remember noticing whining on mine is when I'm going down a hill.
A friend has a 2001 500 4x4 that was well-used when he got it, and he works it hard now. It has had some problems, but nothing major. It can be really noisy, but he finally discovered some missing bolts were allowing the ear-splitting hammering noise, so he got rid of that.
All in all, I think if you keep the fluids in good shape (topped off and changed at regular intervals) and don't drive it under water, it should last a good long time.