GRID is excellent, I just got this afternoon and I've been playing non-stop, first I played about 5 races on single-player and decided to check out online, the netcode is pretty great, your handling is never affected (for me so far) you only see cars popping in and out of existence once in a while but nothing serious.
It's a great arcade racer that also rewards you for a smooth driving style, the graphics are really outstanding (and I love how the UI is rendered in 3D) and it's very fun to play, I'm using a 360 controller to play this, it recognized it right out of the box (Games For Windows thank you very much) and worked out great for driving.
I'm gonna see how the single-player campaign pans out (my first impressions were very positive) but aside from your usual douchebags online is handled pretty well, you can get into the action pretty fast and there's not much downtime (a 30 second timer begins once the first player crosses the finishing line) and there's a pretty sleek voting system, even with the controller it's easy to handle your way through the menus and the chat works relatively well (not much people use it though).
I definitely recommend this game for those looking for an arcade racer that's not too wacky and actually rewards for driving well and smooth, I'm not so sure how it'll play without a wheel or a gamepad but if you have a 360 controller lying around, the experience is top notch right out of the box.