layover at Narita

I have got around 6 hours at Narita between an AA flight and a United flight. Would like to do some shopping, dont really care about leaving the airport but would like to see ALL the shops/facilities. I understand this would mean going thru passport control (imiigration) Do you think that the rest of the shops are worth going through passport control?

airside are all the duty-free shops and brand boutiques, landside are post office, money exchange, restaurants. See: http://www.narita-airport.jp/en/guide/dutyfree/index.html
But I am afraid you will have to change the terminals. AA as a member of oneworld is terminal 2 with oneworld member JAL, while star alliance member United is in terminal 1 with star alliance member ANA.

i dont mind changing terminals, with six hours i can take my time and shop while transfering. I was just curious if I would have any trouble going thru passport control on an international transit flight. I would not be going thru customs though?