RBR provides a rewarding and memorable gaming experience
You start the game by going to the rally school. Richard Burns explains a number of rally techniques to you (his voice work is good by the way - he doesn't sound bored) which you can then have a crack at. This teaches you a few things about rallying (I'm not a fan but it does interest me) and shows you right off this isn't just another driving game you can charge into headlong. What's more I soon felt that the developers worked hard at making this game as realistic as can be, and I admired the result.
This is the game's main quality: it's realism (and thus, difficulty), whether you see it as something that's good or bad. I'm more of an average skilled gamer myself, but I managed to get gold stars for all rally school lessons, and so far I've managed to win rally seasons on the intermediate level.
So I figure there are games you have to want to like and for which you have to be willing to put in some effort. It's easy to dismiss a game for being too difficult after a few tries. But, hey, this is where RBR shines in my eyes, and how I like to look at it: most players will forgo the challenge but those who are willing (and I'm trying to say it's not actually that difficult to get into) will find this game to be one of the most rewarding and memorable rally/driving (even gaming) experiences they've ever had.
The game offers fewer rallies and cars than CMR or WRC; there are six rally venues with six stages each. These are England, Japan, USA, Australia (all gravel), Finland (snow and ice) and France (tarmac). The eight cars are: Subaru Impreza 2003, Subaru Impreza 2000, Peugeot 206, Citroen Xsara, Mitsubishi Lancer, Hyundai Accent, Toyota Corolla, and the MG ZR Super 1600.
The longest stage is nearly 10 miles (14km) long and will take you around 8-9 minutes to complete.
Graphically RBR looks and sounds very good to me. Screenshots don't do the game justice. Use the in-car view and I imagine you will see and hear things very similar to what actual rally drivers do.
As a beginner you will win rallies by staying on the track. The key is holding back; you don't get good times by going from tree to tree and railing to railing at full speed like you might've done in other games. Once you get the hang of it, you'll dare to go faster and faster, and using the techniques you learned, you'll begin to set times dozens of seconds faster than your previous best.
You'll follow the pace notes of Burns' co-driver Robert Reid. There are some useful options in this area: you can have the pace notes read to you a bit sooner or later than the default setting, and you can also choose to have the pace notes appear as signs on the road itself, so you can see sharp turns coming up from a distance.
Driving these cars has been a joy for me (and the more the better I get). Successfully sliding through a hairpin, getting near top speed on a straight and flying over crests at the risk of losing control (whereas in CMR and WRC especially, jumps are a dull experience, at least compared to RBR).
I've found stage replays are worth watching, more than in other games. They look very much like the real thing, and they can be saved onto your memory card (even those up to 10 minutes in length).
Another area where RBR stands out is car setups. You can make the same changes to car a professional rally team can, but I haven't quite started to play around with it (it's a lot to swallow, but it's use isn't necessary I guess until you start playing at the highest difficulty level).
Car damage is also extensive. You can hit a bump and send your car rolling, making it look ready for the scrap yard (though most of the time the car remains drivable). The biggest danger seems to be hitting rocks or trees (and indeed going down hills in some places) which can damage internal systems and at that point you will have to forfeit the rally (note: damage can be reduced and even turned off). I'll admit redoing a stage is a bit tedious as you'll have to go back to the main menu and reload your profile, but at least you can save your progress after every single stage.
That's my review. Hopefully I managed to provide some useful information. Obviously I'm biased so you might want to read some other reviews as well.
If you can get a copy of RBR for your PC I would recommend that, as there are mods available on the net that let you add more cars and tracks to the game.