I've dived in to my first sim racing game, and it's been pretty fun. Gran Turismo 5 certainly pulls out all the stops. Lots of variety, over 25 locations with over 70 track configurations, and all those pretty, pretty cars add up to quite a package. I've been concentrating on the GT Life 'real game' portion to get the full experience, which is quite a package; I'll do Arcade once I learn many racing basics, as when you suddenly go to a fast car, it really takes getting used to, and I'm nowhere near testing myself online yet. I may try to hold off on doing too much, though, as there's a good chance I'm getting a Logitech Driving Force GT wheel/pedals setup for Christmas.

Positives:

• Graphics—Wow, when you're screaming down the Nürburgring on a 73" 1080p TV, it's truly breathtaking. If you really pay attention, you can see the trees are the typical cross-sectioned trees you're used to, but at 100mph who can notice? And the far backgrounds and chalk on the racetrack don't have a hint of fakeness. Driving the London circuit, you feel like you're really driving through Piccadilly Circus as you cruise past the Sanyo and TDK signs.
• Intro Movie—I'm not sure when I'll start booting up the game without letting the awesome intro play. Detailing the building of an automobile from the time minerals are extracted from the earth to when it rolls off the assembly line, the thundering piano jazzes you up... and then it gets really good with tons of great racing action set to My Chemical Romance's "Planetary (GO!)" being displayed, showing you what a time you're in for.
• License Tests—They're a small thing in some sense, but really a needed tutorial if you're coming from arcade racing to sim racing. A nicely done intro to the finer points of racing and you get experience for your racer. Be prepared to curse a lot if you're shooting for all gold trophy times, though.
• Leeway in Car Collisions—Many events/challenges tell you that contact with another car disqualifies you. In practice, some minor scraping while jockeying for position or a low speed slam into the back of a car ahead of you is blessedly overlooked.
• Community Involvement—Earn a car from a challenge that you already bought? They're doled out as virtual coupons that you can gift to friends online for trades for something you want or just to be nice. I've even heard a few have started selling them on eBay.

Negatives:

• Top Gear Challenges: How cheap is it that they could get Jeff Gordon to do a NASCAR special challenge, but they couldn't get one of the show's stars to do the voice-over intro for the Top Gear test track challenges, settling on a random British guy? Also, while it's nice they included it, the track is actually pretty dull viewed from a driving perspective. Honestly, it's more fun watching The Stig test a supercar or Billie Piper do "Star in a Reasonably Priced Car" than to actually drive the track. The challenge where everyone is racing in excruciatingly slow '62 VW Microbuses is very much in the ethos of the show, but without the banter and teasing of Clarkson, Hammond, and Mays it falls flat.
• B-Spec Racing: Imagine a friend got the newest gaming system, invited you over, and instead of letting you have a go, said "You can't play for real. I'll use the controller, you just tell me what to do." That's B-Spec. I suspect it falls right into that wheelhouse of things Japanese probably find amazingly fun, but puts Americans to sleep. It's a massively stupid waste of time.
• A Bit Micromanagy: While some tuning features like new suspensions, turbos, tires, and such are decent enough, the need to do occassional oil changes and engine rebuilds is a bit on the anal side.
• AI Cars Can Disqualify You—During events where contact disqualifies you, if you brake hard the AI cars typically make no attempt to avoid collision, and even though they technically crashed into you, if it's hard enough you get disqualifed for contact.
• Loading Times: Even with loading the game to the hard drive (a good 45 minute chore, despite the claim of '20 minutes to go'), there's a decent load time involved for lots of things in the game.

Still, none of these negatives really lord over the postives. It's a marvel of a game.