First thing you should be aware of is that Next Car Game is not Flatout. It's inspired by those games, it shares some features with them, but it is carving it's own path rather distinct from those old games.
Flatout was largely an arcade fest, with big, over the top features and larger than life elements. Next Car Game, while still being somewhat arcade, is much more down to earth and based in reality. Yes it's not a full on derby sim, there's still the wild crashes and crazy tracks which are a staple of the genre. But the car handling and physics are much more realistic than those old titles, some of the more extreme game elements of the old games have not (yet?) been included in NCG, and the whole thing feels more gritty.
All of the above is, imo, a good thing. Some might object, but personaly I prefer it when it's not quite so over the top.
Bugbear have said that they're trying to appeal to both arcade and simulation crowds though. The game has some very strong driving assists such as traction control etc. which, when turned on, make the cars much easier to just throw around like the best arcade racer, appealing to that crowd. But if you turn the assists off, the handling becomes much more tricky, requiring you to control the throttle, steering and brake inputs very carefully - perfect for sim fans. And in fact many wheels users have commented here on this forum that the game plays fantastically on their setup. So as far as we can see BB are certainly delivering on their promise to make the game playable for both arcade and sim users, and having great success with that aim.
Of course, you should bear in mind the elephant in the room - this game is Early Access. Which means that at the moment, it's buggy, short on content, and still being worked on. As of the current build it has three cars, with a few setup/paint options for each, three derby arenas and four tracks - these can be raced forward or backward with up to ten laps and 23 AI cars. We don't know how long it will take for the game to reach completion, or indeed when we will see features such as a career mode and multiplayer.
However, so far the game has followed a regular monthly update schedule, and while the update may be a little delayed this month, that's perhaps understandable because BB have been working on a very large game engine upgrade which will hopefully perform even better than the one we currently have. And the game is emminently playable in it's current form - if you like the derby racing genre, you should be able to come back to it pretty regularly even with it's current limited content.
Another Early Access perk is that it's price is currently lower than it will be come final release, and updates from purchase up to release will be free. And also that if you buy the game, you get to support the developers in bringing this title to us, and perhaps even offer feedback which will shape and mould the final product into something that you find even more fun to play.
At the end of the day, whether you think this game is worth it or not must be your choice bro. Check out videos on Youtube and try the tech demo from the official site which will show you an example of the physics in action (albeit when pushed to greater extremes than one gets in the actual game). But if you enjoyed Flatout, I would hazard a guess that you should like this too. Personally I think it's better than FO, because as I said above I prefer it's less arcadey style, and because there were certain features of FO which I did not like, but which this game does not have.
Looking at it's current state and current promise, I would recommend it as a good buy. It's up to you if you would agree though...