Side note: I do jailbreak my iPhone 4...
Well, you can turn to these articles on jailbreak:
Why You Have to Jailbreak the iPhone 4 (or iOS 4)
Apple iPad Jailbreaking Hacks - Why Jailbreak?
5 Reasons to Jailbreak Your iPhone - and 5 Reasons Not
Then make your decision
Now the AirPlay is an easy way to stream digital media from the iPad to an Apple TV. And the Apple TV can already access iTunes.
The new generation of Apple TV is not at all better always. It has some drawbacks. For example.. in new Apple TV when connecting the USB port, it is only designated for support & service but issue will be for tweakers.. In old Apple TV , the USB port was worth full to users, when it is limited to maintenance and service needs only and also works good. Better you can maintain the old one.