This game rocks even tho it has a number of bugs on all formats. To get the best experience out of it tho you need to set the AI to Legend as it's impossible to get low end teams in the Top 10 most of the time and makes you fight to get into the better teams.
I'm on 5th Season. In my first season I was on Professional AI and got to about 4th in Drivers championship. Then I re-signed with Virgin for 2nd season and was well into the game by then caned it and won the world champs, my team mate could only manage 20th so didn't win the constructors. It was then I realised I had to change the AI cos I was winning races even if I started in 24th. Because I beat my Rival (Hamilton) I got contract with Mclaren with Hamilton as team mate for 3rd season, but I changed the AI to Legend. I was doing faultless laps in Bahrain and ONLY JUST got into Q3 and then managed to get a 5th place start. I finished the race 4th.
I also started a new account (as you can only have one save) and put it on Legend AI and had MUCH different results which was cool. I raced for Virgin again AND doing faultless laps with all assists off, but now I could only just make it into Q2. The car didn't have the pace even tho my laptimes were same/betterish as previous account. I qualified 14th and finished race in 9th after skemming round as fast as I could. And that became a tough season but you're only expected to finish 18th at end of season so it was well do-able.
But once you start putting in consistent laps you'll find Professional AI is just way too easy. Luckily Legend is a massive step up even when you're in Top 10 competitive cars.
There is a patch coming out soon which is needed as there are quite a few annoying bugs in the game. Sometimes the AI wont pit on dry races and that sux cos you have to. This usually happens tho when you have the race length set short (30% or under) cos theres small pit windows for all 24 cars to pit and not cause huge traffic jam. If anyone on here is having that problem then an apparent remedy is set your race strategy to pit in a lap earlier or later than defualt, or reverse tyre strategy and start on primes so you don't have to pit till later. But it really sucks when your chasing say... Alonso and know damn well he aint pitted and you're tryin to out pit him then give in, pit and go back out and he is still 25 seconds in front of you and remains there till end of race (cheating barsteward).
But all in all a great game. Have been racing online with some guys from the codemasters forums that wanted clean races and it's been superb.