Yaar that all depends on how much you'll play it. Because it's really an intensive game, not to mention long, and the modes in it..... i'll hate saying this because I spent so much money on it... aren't all that entertaining. Maybe it's just because I'm only 4% done with the game, but I honestly didn't find it all that amazing from the "game" standpoint. I keep saying that because from the driving standpoint, it's spot on. I've driven some of the cars they have in the game, and from experience, I know those physics are 100% accurate. Forza honestly has NOTHING on the GT5 physics engine. We'll see how Forza 4 is when it comes out around Aug.
But the downsides ARE pretty apparent. The graphics aren't great- the car is detailed, but the environment seems pixelated at times (especially during rain). Damage is another weird thing which I haven't figured out yet (I think fahdchhapra would know more about that). Oh and the top gear test track events are stupid. I wish they had given the entire runway to players to mess around in.
Would I recommend it...? Yeah. Even with all the flaws, I would recommend it simply because it's GT5, and every car guy should play it.