In short: V-Rally 4 combines the physics and visuals of WRC 7, with gameplay content similar to Dirt 2-3. The quality is very good as a whole, and the customizable gameplay options are superb, but there's some inconsistency in the difficulty of the AI.
Let's start with the positives. The game runs really well on the regular PS4, I did not notice any technical issues, like framerate drops. Visually the game looks really good, but [obviously] not as good as big-budget games such as Gran Turismo, F1 2018 or Forza Motorsport. It's to be expected from a smaller studio, but personally I thought it looked very nice.
You have different types of events to race in: stage rally, rallycross, hillclimb, "gymkhana" and buggies. So there's a good deal of variety. The audio sound is excellent, the engine sounds have an authentic ring to them. The game includes cockpit views as well as bumper-views. Each vehicle has a unique feel to it, the developers have opted for having a collection of vehicles that each feels unique and different [from the others] to drive, rather than throwing 100+ cars at you that all feel the same.
One of the game's standouts is the Management aspect; where you can recruit engineers, PR-staff, and mechanics. Each person offers something unique you can focus on: higher rewards from completing certain objectives, faster upgrades for your engine, and so on. You can switch them out if you find people with better or more specific skills. You also have to be aware of your expenses and make sure you have enough to cover them. I wish it was a bit more complex, like the management aspects in MotoGP 18 or F1 2018, but what is there is still fun to have, I wasn't expecting it to even be there.
Another standout is the extent to which you can customize your experience: you can adjust every major aspect of your vehicle (brakes, suspension etc.) before every race, you can test every track before a race to see if the car-settings are any good, and you can adjust the AI before every racing event (on a scale from 1-100). It's quick and easy to adjust things to your liking.
It's also a rather player-friendly game. You can adjust the physics to be arcade or more sim-like (similar to WRC 7 in terms of technical complexity). You can pick what racing event you'll do next, there's no strict path you have to follow. You can test every vehicle before you buy them.
You can upgrade the vehicles you have bought, the more you use them the quicker they will get upgraded. So there's an incentive to become good with your chosen vehicle(s). I like this relationship-aspect of the game, since you get more attached to the cars you buy. It's more than just a collection of stuff. I wish it was a bit more complex, with more depth and scope in terms of upgrades, but once again I wasn't really expecting this kind of thing to even be in the game and thus it was a positive surprise.
One of the things that made the original V-Rally games unique to me was the all the exotic locations, and V-Rally 4 does not disappoint on this: Kenya, China, Russia, Romania, USA and so on. It's a fun global adventure. It's one of those things I personally always look for in a racing game, I want visual variety; different locations, different sceneries.
The driving though, is what makes this game the most fun. It reminds me a great deal of WRC 7, which to me is only a positive thing, since I really like that game. I was actually expecting them to use the same physics model as in their WRC games, that's why I felt safe in pre-ordering V-Rally 4 in the first place. It finds a nice balance between being arcade and still technical enough to be considered a sim, it depends on how you wish to play it. It never strays into the area of being a Dirt Rally or Sebastien Loeb-type sim experience, instead it's closer to Dirt (1) and the before-mentioned WRC 7.
The negatives. The AI feels highly inconsistent. If I pick an AI difficulty-level of 42, I will win one race by a huge margin but end up dead-last in the next race, despite my performance being the same (in my opinion). So I feel I have to adjust the AI on a race-by-race basis, which is somewhat annoying. It's not a major issue, but still irritating. As I already mentioned, I wish the management aspect and upgrade system was a bit more complex; I feel it's too easy and too quick to fully upgrade your car, it should be a larger goal in itself I think.
To conclude: the fan in me that really likes the WRC-series, the previous V-Rally games, and Dirt 1-4, found this game to be lots of fun to play. As a continuation of the V-Rally series it does a great job of bringing the franchise into the modern era of gaming.