I have a 4th generation 20gig iPod. It's so great, better then I thought it would be. Portable music with a small player and lots of hard drive space comes in handy on so many occasions.
Battery Life was a problem for me at first. It just drained so fast, but the reason was when I recharged it, I usually did it overnight, in which left the iPod completly charged and the power still on to the charger. Now, when you do this, it decreases the battery life because you are feeding too much electricity to the battery and it just screws up. So from my battery last 4-5 hours, I've increased it to last about 8 hours, and now it doesn't seem like it's running out so damn fast.
I also purchased an iSkin recently. It's THE most expensive piece of rubber I've ever bought. But it's cool, protects my iPod. It's like a smart Apple marketing scheme, they KNOW the iPod can get scratched so easily, so they market... protection! Wowee, how convienient, you might say! But even though it was expensive rubber, it's good to have the satisfaction of knowing your iPod isn't scratched by doing a simple thing like putting it into your pocket. But still, my iPod did get scratched before I got the skin.
All in all, iPod pwns.