No it's not a good idea. Too many people hear about jailbreaking and just do it because they can. There's no real reason to do it and it ALWAYS leaves some sort of glitch on the device. It's also a quick way to ruin the device.
It's not a good idea because it makes the iPod very laggy, and some of your apps will quit working. You can always undo the jailbreak, but it stays laggy, and once it's jailbroken, Apple won't fix it or service it. I did it with my old 3rd generation, trust me, bad idea. I had to get a new iPod.