Disclaimers:
This review is for the PS4 , not the PC nor the XOne version.
I'm also reviewing this from the persective of someone using a gamepad, who played in cockpit view, and who is only interested in single-player content.
Let's start with the negatives:
The game seems to have one set of physics for the rallycross racing and a different kind of physics for the stage-rally and hillclimb stuff. Unfortunately the rallycross physics is not good in my opinion, how your car behaves makes it feel like a toy-car made of plastic; one small bump and you flip over. It is by far the biggest issue the game has. It's not terrible by any means, but it's not good either. If you approach it like you would Dirt 2 you'll do OK in these events. It is worth mentioning that you don't have to do the rallycross content if you don't want to, you can just do the stage rally and be happy, there's an abundance of those to do.
Were I to nitpick I would also add: lengthy loading times, one or two interface functions that were annoying to use, and the AI being too strong or too weak on occasion. Smaller things that overall were not serious enough, through magnitude or frequency, to affect the score. As stated, the main issue concerns the rallycross portion of the game. That is why I remove one star from the score.
Moving on to the positive things that really stood out:
The standout feature of Loeb Rally is the sheer amount of content, making it ideal for single-player gamers like myself. Not only do you get a regular Career mode that rivals Gran Turismo and Forza in size, you also get a Sebastien Loeb "career mode", where you get to experience Loeb's career by driving in races he considered hallmarks of his career. To add to this, before each "Loeb event" you get to watch a video interview with him, where he talks about what made that event so special.
Here's another disclaimer: I consider Sebastien Loeb to be the best driver in rally history, 'yes' more impressive than Makinen, Kankkunen, and Ogier. So to me, these interview sections were quite awesome to say the least.
The other big standout of Loeb Rally is that the stages are all directly designed after actual ones. As a consequence, the stages feel highly authentic and are very lengthy for a rally game. Milestone were in fact the first to do something like this in a rally game, and nobody has done it since. A unique feature they sadly did not get enough recognition for in my opinion.
Challenging physics. I would compare the physics to Richard Burns Rally, assuming you have the assists off. The biggest challenge in Loeb Rally comes from the driving physics and not the stage designs, which is the exact opposite of WRC 6 and 7. Yet even with the assists on, Loeb Rally is still challenging to handle, more so than Dirt 1-3. It's still a "hardcore" sim game no matter how you play it.
I would compare the technical difficulty to that of Dirt Rally, as they are both challenging games. The physics itself is quite different between each game, but 'different' does not mean 'bad' ... it simply means 'different'. In the same way every FPS is somehwat different from every other FPS, or how PES is different from FIFA and so on. All racing games demand that you as a gamer are able to adapt to the physics on offer.
Visually, Loeb Rally looks great on the PS4; I had no noticeable framerate issues and the graphical quality was excellent. I would even say that Loeb Rally is more immersive than Dirt Rally in cockpit mode. There's lots of details, for example with dust accumulating on the windscreen. The lighting effects look very realistic as well.
Playing with a controller, the game handles well. Keep in mind the game is very technical by nature, ... so keep that right-trigger in check and don't brake too late!
There were other positives about the game, but they did not stand out to me as much as the above: the sound design of the engines, the livery customization options, and the selection of cars. These were all good but did not wow me as much.
To conclude: if you are a single-player gamer looking for a solid rally game that has lots of content and plenty of challenge, you should really give this a chance, especially if you like stage rally and a good immersive racing game.