I'm not a professional reviewer of any sorts, so please understand that my approach will be rather "unorthodox" and sarcastic, as I consider myself an Asphalt 8 vet. If you want a simple verdict, check out my summary.
Let's get some changes noted and addressed, and I'll leave some more comments down at the bottom:
1. In A9, manual controls do NOT include a button for manual acceleration, it's always auto-accelerate. As a self-proclaimed racing games fan, I call this nonsense (I'll give some lenience to mobile players).
2. For the Asphalt vets: We DON'T need tutorials (I sunk 344 hours into A8 to get all the achievements, I'm not a noob).
3. Touch Drive? (which is an auto steering mechanism of sorts) Racecars have never had the ability to drive themselves and putting that in ceases to make it racing.
4. Drifting feels like a forced auto function in A9. Drifting should be a skill you acquire and learn to use.
5. Boost works while you're airborne. RUBBISH! (Sorry, had to say it)
6. ALL cars in A9 work off the car system from Xtreme, where you can only race x# of times before a rushable "cooldown" starts (in some cases can be rushed by ad-watching). This is garbage and an obvious cash grab, which I will call "pay-to-progress." Let the players grind if they want to for Pete's sake Gameloft!
7. Turning apparently has an auto braking function, which has a rather extreme affect, no matter how little you turn.
Now, other comments (some good things included):
As with all FTP games, there will always be a premium in-game currency; I thought it was very nice of Gameloft to implement an actual system (challenges) for players to use and earn said currency, outside of competitive events, even if it is small amounts.
REAL Achievements! This is the one thing A8 really lacked (20 for 200G? Too little, not to mention A:Xtreme had 0 for 0) that would have made it really good.
From all the trailers/screenshots/clips I've seen, the graphics in the game look really good, an obvious upgrade from A8. However, for whatever reason, the game refuses to let me max out the settings on my 4K laptop. Shame.
A9 introduced a new system in the game, garage level. While an interesting concept, where your "rank" or "level" in the game is determined by your garage, and how well-upgraded your cars are, I think it could use some work with rewards and benefits to having a higher garage level.
Now, the single player campaign/seasons mode: I get that there's a need for something to look good and sorta flashy, but the circuitry board/web design they have for race selection in the seasons takes way too much time to scroll through, and honestly, I find to be a headache. There is beauty in simplicity, as was with A8, and A:Xtreme (was different, to be sure, but overall simple).
Paint jobs: I've NEVER played a racing game that required you to be a certain "level" with a specific car to be able to paint it, which is with the case with A9; I'm calling nonsense on it. Also, even though A9 is in its early life-stage, I think the lack of decals (like the smorgasbord library there was in A8) is really sad.
Offline play is also apparently absent from this game, as noted by my club member Ordin Deeps.
A8, in my opinion, was an example of what a decent FTP racing game should look like: a good-looking, skill-based racing game that allowed you to grind and earn what you wanted to buy, upgrade, and customize, without spending real money. A9, on the other hand, really only looks good; it's a lemon that's only been painted up and re-upholstered.