At the time of writing this review, F1 2013 is my most played game by at least 3X the amount of hours over any other.
However it is not for everyone. If you don't enjoy going around 20 tracks over and over again for hours then this game is probably not for you. On the other hand if racing around famous tracks such as Monaco at high speed, fighting against some of the best drivers in the world for position and avoiding (or not) huge crashes then I'm pretty confident you'll enjoy this game.
The main attractions for me is to do with perfecting my racing line, braking points and generally putting in faster lap times again and again. I have also enjoyed modding the game - which isn't intergrated but is relatively straight forward. Mods can do many things to the experience of this game such as increase the damage taken from even the most gentle touch of another car, to increasing the logic of the AI to make them perform better. The final thing I have enjoyed most is the wheel to wheel battles with other cars.
My Friend, ABigPurpleGoose, and I have thoroughly enjoyed the co-op chanpionship and are currently on our second playthrough fo it.
The AI can be very quick and you'll notice this especially when they are supposed to be on worn tires with you. They seem to have reduced tire wear or at the least some form of traction control to help them as I'm sure they would not be able to handle driving without one of them. As previously mentioned, mods can improve they're logic. For example, if they are next to another car and they're coming up to a corner, the car on the outside will always win except in a couple of corners like the hairpin at Monaco. The mod can help to remove this significant flaw which certainly spoils the enjoyment. Their very basic logic is the only gripe I have with the game.
Finally, don't buy this game on PC expecting loads of people to be playing online, I have tried many, many times and never raced another human outside of the co-op championship.