Good: Free Apps and stuff
Bad: Can't really think of any. But there's probably more than those 2 things lol
Last time I jailbroke an iPod was when the iPod 2nd gen 1st came out.
it only lags alot for me when i install lots of packages in cydia. but i heard the ipod touch 5g will be announced on september 12 along with the new iphone. september 12 is a confirmed event but they still don't know what apple will unveil :0
Jailbreaks cancel out any warranty, so if your a clumsy person. No, and the jailbreak relies completely on the programmer.
IMO learn how to freak and create your own Custom ROM, or make it into a scanner. That was my first phone project lol.
Every iPhone that oi have owned, i have jailbroken. I have never had any problems besides it slows my phone down from little to none.
I recommend doing it man, it makes your phone like 100x better and amusing.
Pros:
Wifi Tethering
Free apps
Themes for your phone
Ability to customize your phone to your liking.
Cons:
Little to no slow down of your phone
Void warranty (all you have to do is restore your phone)