The major drawback in my opinion is the rival ally mode, well some aspects of it.
When you start out career mode, you'll find yourself making more rivals then allies on the track. I've made about 10 enemies among the Winston Cup drivers like Dale Jr, Matt Kenseth and surprisingly Kevin Harvick.
However, you can press R2 and try to share a draft with them, that'll probably get them on your good side especially on a superspeedway like Daytona or Talladega.
Career Mode is a bitch because you have to work your way from the ground up. You'll find yourself spinning out more times then winning. However, I managed to stay in the top 10 in the first 10 races I've run. Surprisingly, Kevin Harvick is in the lead

I had to mention that ! Like other EA Sports titles, the game features a trophy room, where you could see all the trophys from the races youve won.
You cant build engines and chassis unless you expand the R&D Department and the team headquarter more. That's a bitch too.
However, I like the three and four wide racing, EA has made a great improvement in that.