I replied in another thread on this track and thought I would repost a new thread as my review of the product.
I received one of these for Christmas this year. My 4yo and I have had a blast playing with it. I did have some problems as others have mentioned with the heavier cars as well as another problem with the pins. They would not drop completely thus interfering with some of the cars. I called the manufacturer about this and he offered a solution. Apparently the springs that hold the pins up are too strong for the motors and will keep the pins from dropping all the way down. He suggested that I stretch the spring down so that the motor doesn't have to work as hard and has a shorter distance to fall. I did this and it fixed both problems. My heaviest cars now launch just like the rest and there is no more interference with the pin being in the way.
Now my only other problem is with tied races. If the cars finish with the exact same time, the race is automatically given to lane 1. I'll need to get some more track to hopefully spread the finishers out a little more.
I'll also be getting some orange banked turn track to create a return for the cars after their runs are completed. Its already a long walk down to the other end.
The manufacturer/developer of this product is very easy to talk to and really wants it to be successful. If you have one of these and are having issues, give him a call. He might have a suggestion.