My essential tweaks are Infinidock and Infinifolders, which eliminate the limits on how many icons can live in a particular place. Useful if you've got more than 12 of a particular type of app or want all your most used things in the dock.
If you use at&t, add my repo
www.pepper.net and get the att logo and fireball icons.
Another great one is FakeClockUp which makes the animations faster.
I almost forgot iKeywi, the 5-row keyboard. And Wifi Analyzer and Wifi Booster. All quite useful.
FYI, I highly recommend the iPhone 5. Using Speedtest I've seen LTE in excess of 50Mbps.