Has more in common with mario kart than with forza. If you're looking for a serious racing game, this isn't it... but if you've already beaten plants vs. zombies and peggle and are looking for something mindless to do while listening to audio books, this will fit the bill perfectly.
The only multiplayer mode is concurrent time trials, which works quite well. Since you're mainly racing the clock, you can restart the race at any time and won't be unduly affected by lag or cheats. However, the lack of variety means the game itself won't hold your interest for long unless you're playing with friends or also listening to podcasts at the same time.
All cars in a given race mode handle exactly the same. There is no car customization outside of your car's paint and model, but that's quite fun in itself. No plot. None of the annoying interruptions that are so common in other racing games such as cutscenes, slow menus, and crash cams. You can jump directly from one lap to the next. There is a 1 minute delay between races every time the server switches tracks, but otherwise the fun is uninterrupted.
There is a huge number of tracks but all are constructed from the same set of sections, so the variety is limited. Most tracks can be driven fairly close to top speed for most of the race - late braking isn't a part of the game. The game is mainly about finding the shortest path through the track that doesn't result in a crash.
The free version requires spectating every few races but otherwise gets access to most of the content. This isn't pay-to-win. Free players don't play at a disadvantage. I paid for the full version and I found it to be worth the price in order to play uninterrupted. Paid players also get access to several other modes including many tracks, different track types, and a new type of car for each track type. Unfortunately, the paid servers are normally empty so you'll still spend most of your time racing the same tracks as the free players.
If you think of this as a casual game, you'll get some fun out of it. If you're looking for a realistic driving sim, look elsewhere.