This game has 3 main modes: Arcade, Project Gotham Career and Xbox LIVE Career.
The arcade mode is split into various chapters, each chapter has a number of races and in each race you can earn up to a maximum of 2 medals (One for Car, and one for Bikes). You get awarded a different medal depending on how hard you set the difficulty, from Steel up to platinum. It is very similar to PGR3 with the medals and tasks that you have to achieve.
The Career mode is a little different as you work from a calendar and can only move on a date if you have participated in a race. This makes the game more interesting and means that you have to play through a few seasons before you have completed all the tournaments in each ranking.
The Xbox LIVE mode is similar with the ranking system except there is no calendar. I haven't played this part yet, but it looks pretty good.
Another part to the game is Gotham on Demand which is a channel where you can look at other people's photos, replays and live matches.
Finally onto the review, graphically it is impressive, went it rains you can see the reflection of the road on the car which is a nice extra. Game-play is awesome as there are so many different types of challenges that await you. The amount of time to complete fully may be into the 100 hours possibly.
The physics are pretty amazing and it makes it into a real racing game competitor as you can play it while ignoring the Kudos if you will which I tend to do at the start of the career and during harder races.
I recommend any racing fan to buy this game, for people who like to showoff this is a must and for your average casual gamer you can't go wrong as it is so easy to pick up.
Fingers crossed for another one in the series