As many of the other reviews have stated the initial thought of the game are wow Im never going to be able to play this with the new defending techniques being difficult to master. This resulted in around 10 matches of 5-1 & 4-0 defeats and plenty of screaming at the TV!
With practice and patience you will get to grips with the new defending system and although I have yet to master it but I can control it and you feel much more in control of the player and his decision making rather than the hunt the ball down system of FIFA 11. Apart from the defending the look and feel is a massive improvement from the last title with realism at an all time high in my opinion visually.
As an online gamer the most frustrating thing about the FIFA titles is a player quitting half way through a game. This is one of the reasons I stopped playing FIFA 11 unless it was against my friends. In FIFA 12 the introduction of head to head seasons means that a player can still quit but after 5 mins on the clock has passed you are awarded with the win whatever the current score line. With the addition of promotion and relegation depending upon the number of wins you get within 10 games there is something to strive for with opponents becoming better matched to your level throughout the promotions.
With the online factor in this way I would say this FIFA is definitely worth a buy but make sure you stick at the defending and you will ultimately love this FIFA title. If EA sports would get rid of the quit button in matches it wouldnt be far off perfect for online gaming.