Unfortunately I found Grid Legends to be very bland which is surprising as I enjoyed Grid and Grid 2 on PS3. I also liked Dirt 1-4 and Dirt Rally. I'm not sure what's going on at Codemasters but this, Dirt 5 and Onrush have been really underwhelming.
First off the good. It works, looks decent, runs fine and I got it from PS Plus. There is a good amount of tracks and cars. It's kind of fun just driving with reckless abandon, smashing into other cars and clipping walls.
The biggest problem this game has is the way cars feel to drive, which is a massive issue for a racing game. They don't behave at all like you expect a car to, the physics are just weird. Driving feels stiff and simple, you really need to try hard to lose control. For example you can drive a RWD car in the wet with no traction control and just floor it without any concern for wheel spin. It's like the developers didn't want you to be able to fail. So it's not realistic at all but it also doesn't deliver arcade fun. It also does not find a balance between realism and arcade thrills. It is just bland.
The story mode was thoroughly boring and I quickly started skipping cut scenes. The career mode is grindy and you get tired as one dull race bleeds into another. You can try to keep things fresh by constantly changing the type of vehicle you are racing. I found the stadium trucks to be the highlight. There is also drifting which they also somehow made kind of boring. It's like the whole game was made as safe and uninspired as possible. They didn't want to allow players to suck at it.
It's not very good but doesn't do enough to make me hate it. I can't recommend Grid Legends unless you got it with PS Plus or are desperate for another racing game.