OK, I've given this a proper go now, and it's good fun. It isn't fancy or flashy, but it does play well.
I like the idea of the different licence and race levels, although I can't help thinking that maybe a couple could be taken out - there isn't much of a noticeable gap over the five speeds, so maybe four would be more appropriate. Likewise, I don't really see the need for four difficulty levels in each category when Formula Three isn't much tougher than Formula Four. I can see why it's there - and obviously it sounds strange to suggest taking something out of the game - but I think it's just a little superfluous, although the developer may disagree.
The gameplay is about as straightforward as a racing game gets, which is no bad thing as it's done well. It's responsive and intuitive and all the better for it's simplicity. The only criticism I can think of is that collisions with other cars occasionally produce slightly strange results in regard to the player car's positioning. However, this is a minor and uncommon irritation and doesn't get in the way of enjoying the game.
The graphics are fine, just what a game like this needs - functional and fun and undemanding on any system. Similarly, the sound effects add little in terms of gloss but are fun all the same.
I've had the game crash once, and it resulted in me losing the licences I had acquired on that run. It's not a problem I've had since, but it might be worth quitting on the menu screen and restarting every now and then to save any progress, as it doesn't take long to start up again.
Anyway, a good job. Not earth-shattering by any means, but a pleasant and addictive game to play and well worth a download.