I have to confess, I like the UI of my Kindle Touch a lot.
I would say, though, that the browser is terrible, so use
http://www.fabiszewski.net/kindle-browser/
Also, the screensavers hack is a must-have, if your device is non-SO.
Better jailbreak IMMEDIATELY, though, and
DON'T TURN ON THE WIFI because if you get an OTA update to fw5.6.1 you are screwed....