Nothing. My ZR2 rocks and it is the best 4x4 I have had in a long time. The truck handles great and I have tried to get it stuck and I just can't. I go where I want to go.
The truck has plenty of power and has good torque for its size.
My 2000 Chevy S-10 ZR2 was the best truck I have ever owned, and the fourth S-10 I have owned. I had the automatic with the big V6 Vortec. I've owned two ZR2's. The first was a 1996.
Unfortunately, I totalled the truck on December 21st, 2008 after losing control when I hit a snowdrift with ice under it.
I own land in N. Wisconsin that is about a half-mile offroad, with only old logging roads to get to it, with much of it hilly. In all conditions, including wet leaves, mud, and a foot of snow, it was impossible to get the truck stuck. I am leaving for duty in Afghanistan this week, and when I get back in February of 2010, the first thing I am going to do is buy myself a 2002 S-10 ZR2 in good condition with low miles.
One thing I should mention is that if you do a lot of off-roading, you will have to replace the upper and lower ball joints at about 100K miles, as they will go bad. Good thing to replace the front wheel bearing assemblies at the same time. This is easy and relatively inexpensive to do if you have any mechanic skills or know someone who can help you. Oh, my truck had 138K miles on it when it was totalled. I damn near cried when I did it. I loved that truck... and I don't want to drive anything else. Oh, one more thing. Make sure the 3rd Door mechanism is properly aligned and lubricated if you are breaking the opening latch. That will take care of it. They go out of alignment and that plastic handle just does not hold up.