So I played this also last night, and give that it was my first time ever, it's very easy to get into.
I checked online because I wasn't sure what was different from the really thing, well except for one really obvious difference.
You role the dice by moving the stylus back and forth on the touch screen until you hit the green zone on the bar. Not as bad as it sounds I promise. The scoring the same except there is no "oinker" or "piggyback" scoring, just "pig-out". And also every-time your score one of the hands, you're give pig-bucks which you collect to upgrade your pig. This is essentially adding weight to one side to increase your chance of it landing there but you lose the upgrade if you "pig-out".
There are three options of play. 1 Player is where you are given five rounds to score as much as possible and get on the High Score Table, 2 Player allows you to play a friend by taking turns on the same machine, and World Tour is against computer opponents of increasing difficulty.
The opponents are represented by cartoon characters that lean heavily on stereotypes, and the backgrounds and music changes to match the environment. The AI early in the game consists of stopping once they scored a set score for their go, for instance one character always stopped at 15, even in the last round where he had 95 and I had 90 and he still passed. It does becomes less noticeable as the game goes on though, although you do get the sense you were protected from getting "pig-outs" earlier in the game.
I'm not sure about the upgrading during the game, although I suppose it adds another level of risk and strategy, and the purists don't have to upgrade if they don't want to.
Although it's OK as a 1 player game, I think this is better suited for 2 people travelling, who remember the table top game fondly.