4 stars: Not as bad as I expected. The ads are frequent but most can be muted, and skipped after a few seconds. I was happily surprised by a nicely done hidden object mini-game. That makes this game better. The level difficulty advances slowly, but you get offers occasionally to try Boss Levels which can be more fun if you want a greater challenge sooner rather than later.
3 stars: A fun concept, but clearly designed to maximize ad playing. It doesn't get harder; you have to keep playing super easy levels waiting for the occasional challenging one. The UI is buggy... sometimes the car goes right through a pedestrian, or two cars overlap on the road, etc. The races are clearly fake; you aren't racing other people, they just want you to keep playing and watch more ads.
2 stars: I like this game...except for the frequency of commercial breaks that freeze and I have to get out of the game and restart the level. This game has better structured ad breaks, they don't seem to be disruptive and are placed when you complete every 2nd or 3rd level. The thing that is making me lose interest is that the levels are super easy and you have to complete them in order to get to the challenges.
2 stars: it's an okay game but it's nothing like I saw in the ads! the cars look different,there are less cars,it's telling me what to do (I HAVE SEEN EVERY COMMERCIAL YOU THINK I DONT KNOW HOW TO PLAY?!) too many ads, and it's a little boring, but if you're into sorting games and stuff like ...